Thanks for the answers so far
Personally, I carry around 6 memory cards:
1x 128mb (I had this for storage on my PDA)
2x 512mb
1x 1gb
2x 2gb
None of them came with my camera, so I started with the 512mb and 1gb cards, and since then have found great deals. I have mostly Sandisk, but also a Toshiba and PNY (I'd be shocked if at least one wasn't a rebranded Sandisk).