There are several out there such as this one and one I also use is justfreestuff.com .

I also use sweepstakes advantage because you can tag each one and it keeps the date you entered. I also like that it sorts them by categories. Every few days I go in and go through all the ones that are expiring soon. Now, the bad part...there is a lot of "garbage" contest on there. Tons of blogs, companies I have never heard of, etc. They also keep an archive of closed contest. That was helpful to me when I won the NYC trip and wanted to see what was included and the rules.I have learned how to go through it all very quickly and I pull up my own list once a week to see where I am on contests.

I use alot of other sites, though I don't feel any are especially "lucky". Are you interested in certain types of prizes? About Sweepstakes.com also breaks down contests into categories. No blogs. Personally, I have won a few nice things from blogs.

sweepstakesmama
contestsabout