NOTE: If you're interested in OneNote, Microsoft just released a free mobile version for Android and Windows Phone 7 smartphones. You can also play with a stripped-down, browser-based version of OneNote if you have an MSN or Hotmail account and you add the free Windows Live SkyDrive feature to it...just start using the Office 365 features and you should be able to access the browser-based version. Last, Microsoft will let you download a free trial copy of OneNote at the Microsoft Office website.
The #1 problem with OneNote is simply that no one I run across seems to know what it is. However, if you take just 5-10 minutes to poke around you'll find that Microsoft OneNote is the most useful part of the suite that you never knew existed.
Put simply, OneNote is a place for your stuff. Think of it as a switchboard for MS Office. OneNote lets you organize groups of topics into "Notebooks". Each Notebook you create has a series of tabs across the top (called "Sections"), and each Section contains one or more pages. The structure is similar to a filing cabinet, with tabs, folders, and files, but because this is a piece of software we're talking about, it does oh so much more.
The goal behind OneNote is that you should open the program and immediately be able to start working. The is no Save button, anywhere: everything you do is saved in realtime--that way, you don't have to think about anything but what you're trying to do. It isn't designed for detailed text formatting like Word, but it is smart enough to auto-create some of the things you commonly use, like bulleted lists and tables of information. For example, if I want to start typing rows and columns in a grid, I simply...start typing. Hit tab and a grid is created, with the cursor scooted on to the next cell every time I hit tab (and new rows created when I hit Enter). I can pick bulleted lists from the toolbar, or I can just type a dash and a space and OneNote gets the idea that I'm enumerating--and of course it does the same for numbered or lettered lists (a., b., c., etc.). This makes it easy to just sit down in a meeting, start taking notes, and dress it up later if you want to. I have a handy "Meeting Minutes" template in MS Word. I type my notes in OneNote, and when I'm done I open the template, copy/paste the notes into it, save & send the document, and I'm done.
This becomes a huge benefit when you realize that OneNote is searchable: if I need to find which meeting it was when my team talked about X, I just search OneNote and get a listing of all references. I can dial down the results to one Section of tabs, or grow it out to every OneNote Notebook I have. What blew my mind was when I dropped a screenshot into a page and found that OneNote used OCR to pick keywords out of my picture! Searches are fast, and the best part is that OneNote will let me get away with being sloppy. If you want to take a "junk drawer" approach, you can start dumping files of all kinds into OneNote. When you paste a file, you are given the options to drop it in like an e-mail attachment (has an icon, you double-click, and it opens), as the content (dumps the contents of the doc into the page), or as a link to the place it came from. If you copy/paste information from another place, including the web, OneNote will automatically drop a citation link in for you, be it to a place on a network, on your hard drive, or on the web.
But that's just the beginning. You can share your notebook across computers, across a network, or via the web. If you have a Windows Live SkyDrive account, you can get Cloud-y and use SkyDrive as a nexus so that no matter where you are, you can get to your Notebooks and sync them across machines. Shared notebooks can be restricted at the notebook level, by section, or even by page. You can encrypt and password-protect. You can log into your MSN account and access SkyDrive to work with your Notebooks if you're on a computer that doesn't have OneNote installed. You can move notebooks around, merge them, and more. You can record meetings with your computer's microphone and it'll be saved directly into your Notebook or out to a separate file. You can also use a screen grabber to take screenshots of just about anything.
OneNote also bridges the gap across programs: you can "Print" to OneNote, e-mail to OneNote, or right-click a file and "Send to OneNote". If you're feeling lazy, you can just point it at OneNote and go, without telling it what to do with the content...OneNote will put it in a section called "Unfiled Notes" and let you sort it out later. If you have a tablet-based computer, drawing tablet, or even one of those old "pen-based computers", you can draw directly on the screen. There are drawing tools, too. Or if you just like drawing and don't have any of those, you can mark up your notes using the mouse, just like freehand drawing in Photoshop.
So here are two very good examples, work and home, of how OneNote can be the Right Arm of Microsoft Office:
I manage IT Projects. I have a notebook for each project, with sections labeled "Overview", "Initiation", "Planning", "Development", "Testing", "QA", "Production", and "Meetings". Each phase of my project has important information in the appropriate section--for example, "Overview" gives the history of the project, who asked for it, why we're doing it, and who to contact. When I'm in a meeting, I open the Notebook, start typing in a new page in the "Meetings" tab, and when I'm done I copy/paste into my Template, "Save As", and e-mail it. It makes quite an impression when the people in my meeting have the minutes waiting for them before they get back to their desk.
I had a real problem with Post-It notes: I loved them too much. I'd write stuff down on these sticky colored scraps and they'd end up everywhere. Sifting through them to find the one I was looking for was annoying.
I made a OneNote Notebook with sections for each logical group. Now I have a "Contacts" Section for people/companies' contact information that really doesn't need to be in my Outlook Contacts--or information that doesn't fit on my phone, like mailing addresses. I have a "Computers" section that has separate pages for each computer, with specs and information I need to know at a glance. Most importantly, "Electronics" - all the stuff I have that I sometimes have to go back and fool with. My Onkyo receiver, Samsung Flat-Panel TV, PlayStation 3, and more have their own pages with notes on my settings and copies of the user guides. If I buy something online, I no longer print my receipt, I just choose "Send to OneNote" and point it at my "Purchase Receipts" section, where it gets its own page. VERY handy when I have to find out when I bought something or need 'proof of purchase' because it needs to be fixed. Ditto for rebates and the rebate forms I mail out. I know people who have sections for "Recipes", "Job Interviews", or even "Family Tree".
The Work notebooks I sync across our network and share with other people. The personal notebooks I password protect and sync through my SkyDrive account. Either way, I now have a way to access any information I store, no matter where I am, and search it without having to dig through a ton of files and folders.
If you have a lot of information, of any kind, and you need a decent way to get your arms around it, you couldn't ask for something more simple or more useful. I've been a fan of OneNote since I first gave it a try four years ago, and I'm glad to have a chance to share this secret with you.