Even if you are not listed on the registry (for whatever reason), you can still cast a provisional ballot. Wreak havoc with the system.
If you live in Maryland or the District, polling places are open tomorrow from 7AM to 8PM. Virginia polling places are open from 6AM to 7PM.
Virginia residents can locate their polling place at this site. You may also find contact information for verifying your Voter Registration status here.
Maryland residents can locate their polling place at this site, though it requires information that is located on your Voter Registration card. (If you do not have that information, you may contact your County Election Office.)
District residents can located their polling place at this site. You may also check your Voter Registration status here. There is contact information for the Board of Elections and Ethics here, in case you need additional information.
Keep in mind, if you are a registered voter, you will only be allowed to vote at the appropriate polling station. So, unless you fancy a lot of extra driving and line-waiting, do your best to determine beforehand exactly where it is you are supposed to show up. And bring a walkman / book / iPod / PDA / water bottle / etc to pass the time, as there are likely to be lines. And a photo ID is essential. And hey, if you have your Voter Registration card, why not bring that, too?
I think I have used up my political posting bits for the year, now, and I'm going to go back to my corner.
Brockman: This is Kent Brockman reporting from ... my own home, in accordance with the new curfew for anyone under seventy.
Marge: Mmm ... I can't believe that passed.
Lisa: I warned you guys that seniors always vote in record numbers!
Brockman: The controversial measure passed by a single vote.
Marge: Oh, you really should have voted, Homer.
Homer: Pfft, it wouldn't have made a difference.
Abe: [from window, with flashlight] Lights out, you punk kids!