Memory cards are increasingly commodity items, but here is what you need to know before clicking the buy button:
SDHC - Secure Digital High Capacity. These cards are not compatible with older regular SD equipment. If in doubt, check first. Newer kit, especially DSLRs which need the extra storage, almost certainly are ready for SDHC cards.
Class 6 - The Class is the speed for reading/writing to memory. The existing Classes are 2, 4, 6 and 10. High resolution DSLRs need class 6 is you ever plan on taking sequential shots. Class 4 is absolutely fine for regular pocket-sized digital cameras. Class 10 is new and is for the extreme professional level.
Verbatim - Better known for blank CDs and DVDs, Verbatim make good quality memory cards with consistent reliability.
Price - Shop around and consider your true requirements. Depending on your camera and likely usage, two 8Gb might well be as useful as one 16Gb card, but cheaper. Likewise with two 16Gb cards and one 32Gb card.
For DSLR use, highly recommended. Five stars.