Ya, been looking around for a thumbstrap stylus, it'd be really useful for Mario 64 and Rayman.
Otis, I don't think there's a significant speed difference between memory card adapters, just memory card brands. I have a cheapo memory card, crashes on some games (rub rabbits and spiderman), but i only experience slowdowns when there are movies (eg. in Castlevania).
oenone, let us know once you get your ds.