I use use Firefox with the iMacros plugin.
Just go to Tools>Add-ons> and click on Get Extensions in the bottom right corner.
That will take you to the site where you can download it. Just type macro into the search box and it should come up. Then install it.
It comes with a tutorial but basically to use it you go to the poll page then click the iMacros icon which will be up by your address bar. Then go to the Record tab, click Record, then select Ron Paul on the poll, click Vote, wait for it to go through then click the Vote Again button. Then click Stop in the Record tab. Next open the Play tab, under Max put how many times you want to run it (I put 5000), then click Play Loop and it should start voting. If you have a slow connection you might want to go to the Edit tab then click Options and raise the timeout limit. I suck at explaining things but it should be pretty easy once you see how it works.