If you know please post a link to it.
If you don’t know for sure, please post a link to the biggest one you do know of.
As an alternative, please post a link to the biggest one you voted in.
Here’s one to beat:
How old are you?
03-02-2010, 04:55 PM
Giles
Voters: 600
The most votes in a poll that I started have been in
Poll: The Best All-Time TV Show [vote for up to 10] ( 1 2)
05-08-2010, 07:40 AM
Zeldar 05-23-2011 02:21 PM
by Elendil’s Heir 69 9,520 Cafe Society
Multiple Choice Poll. Voters: 298
The most votes in a poll I voted (and posted) in have been in
Do you do a “Thank you wave” when someone lets you merge in traffic?
09-17-2010, 08:17 AM
Voters: 348
It will take further research to locate polls I voted in but didn’t reply in, which is a flaw (in my way of thinking) in how records are kept on SDMB polls. Polls that don’t have any replies beyond the OP’s comments vanish as soon as they’re off the “front page” of whatever forum they’re in.
Here are some in-between sized polls:
Poll: A poll: ROCKY HORROR PICTURE SHOW ( 1 2 3)
10-25-2010, 09:34 PM
Sampiro
10-31-2010 11:50 AM
by MeDrewNotYou
120 4,399 Cafe Society
Voters: 411
http://boards.straightdope.com/sdmb/poll.php?do=showresults&pollid=2538
Poll: Poll for people who wash their hands after using the bathroom. (Please read before voting.) ( 1 2 3)
04-01-2011, 08:15 AM
Agent Foxtrot
04-12-2011 12:54 PM
by AHunter3
105 3,829 In My Humble Opinion
Multiple Choice Poll. Voters: 445
Poll: Religious Poll ( 1 2)
09-22-2009, 03:54 PM
TWDuke
05-10-2010 05:42 AM
by ivan astikov
92 2,905 In My Humble Opinion
Voters: 493
This one is interesting as it shows (incidentally) how well dopers follow instructors.
It had 86 votes, 80 replies, and 2,554 views.
One of the best threads this year!
Okay, here’s another tack to take.
Before The Polling feature is enabled. Here’s how to use it. started 09-22-2009, 01:00 PM by Gary “Wombat” Robson ( Voters: 347. This poll is closed ) were there any polls at SDMB with the features we have these days? If not, you only have to go back less than two years to see all of them!
Who holds the record for the poll with the most voters?
Giles with 600?
Why don’t we have a directory or reference place for polls we might want to participate in?
Why not just ask for a pony, while you’re at it. 
Can I have a pony?
edited to add: Please?
Okay. Can I have a pony? 
HEY EVERYBODY!!! samclem IS GIVING AWAY PONIES!
lines up
(never mind)
It might be that Spit or swallow thing from long ago.
Quite so. It could be any of those threads where the “poll” wasn’t one that counted the votes. I should have made that aspect clearer.
How old are you? started 06-02-2011, 03:33 PM by Anaamika has just passed the 500 Voters mark and is still going strong.
At this rate it has a good chance of overtaking How old are you? - In My Humble Opinion - Straight Dope Message Board and its 600 Voters.
Jump on board if you haven’t already! 
As of just now:
How old are you?
06-02-2011, 03:33 PM
Anaamika
What age range do you fall into?
Voters: 608
Congrats!
It’s been a good while since the latest post here. Any contenders to add to the list?