This inspired me to try with Javascript turned off, and sure enough I can choose multiple options. There was no obvious error so I assume my all-choices answer was processed.
Some sites can justify breaking if javascript is off, but not yours.
edit: Additionally it seems HTML is not escaped at all. I should have used something more obvious than just <b>ing the comments...
In my head, a survey has more than one question, while a single question is a poll. So, the name of the site made it seem like you'd be competing with surveymonkey, which would be a good thing.
Just a note on design. I have an unnecessary Scrollbar with Firefox on Linux (Ubuntu 9.04). Oh yeah and I would suggest you create a Favicon, the green check comes to mind first.
Overall - quite nice, but needs simplifying and tidying up.
Get rid of "win iPhone" insert. It takes away more from the site than it actually adds to it. Also the "Tags" column solves the problem that I'm not sure exists. But it sure does clutter the page. I'd get rid of it too until you are certain that the user experience is (dramatically) improved by having it there.
Why do you have such a large space dedicated to categories when most don't have any surveys in them (yet)? It'd be more useful if there were either less categories or a count beside each category link displaying the number of surveys within each given category.
Hmm..as of using it, maybe if you can make it like a widget where i can link it to my site, that will be more usable (at least for me) in terms of setting up polling system.
I think you should move the "flag as spam" flag icon away from next to the category name; the current position made me think the flag was either a property of the category or a button that would let me flag it like in email, that is, save it for later.
1 bug: When I click sign up it says log in as the title of the box.
1 annoyance: the results page took ~10seconds to render. Mostly because you are using many copies of a fixed size image to render the bars. Why not resize a single image or just make it a html element?
Remove the categories pane completely.
Replace checkboxes with buttons - clicking on them will cast the vote.
Use the common categories from Digg / Stackoverflow and others (Top surveys, Controversial, Upcoming)