As I suggested in the comments some time ago, here's something I've been wanting to set up a big event for the Dreamcast's 10th Anniversary since it's American launch (because 9.9.99 is the date everyone remembers) and here it is. The poll was so big that instead of placing it on the side here where it would look rather ridiculous I've set up a temporary blog for it. You can vote for as many or as few games as you like, and you can also edit your picks too. The poll is open for 30 days.
Take note just reading through the list may take you a while, so wherever you want to pick every game you like or just your absolute favorites is up to you. There's 385 games to vote for spilt across eight polls (because it errored out when I had it as one large poll). That's almost the entire consoles library, Japanese, PAL, American, even indie releases are all included.
The poll will close on 4th September and the results of the top 100 (and the bottom 20, and maybe even the entire 385 if there is enough demand for it, will be revealed on good old 9/9/09. I really hope this becomes the definitive poll of everyone's favorite Dreamcast games anywhere, so the more people who vote the better. Get stuck in!