Check out the list. If you're interested in voting, read up, watch up, ask around and pre-register for a membership (supporting or attending; attending only matters if you're, well, planning to attend) to L.A.con IV.
BTW, just so you know (and I made this mistake myself):
Vote Splitting is a myth!
Hugo voting is by preferential ballot. If you want to see any episode of Doctor Who win the Hugo for Best Dramatic Presentation, Short Form, vote your favorite episode as #1, your second choice as #2 and your third choice as #3. If your #1 gets knocked out of the count early, you're still helping the other two towards the finish line.