Posting this here because I never would have known about this if I hadn't read it in a jam comment a year or so ago.

If you go to to the event page (ie https://ldjam.com/events/ludum-dare/50, or any previous jam), go to:

Ludum Dare 50 > Me > My Grades

...and you'll find a handy list of all the games you've rated! Super handy if you're like me and have a really massive/messy browser history. Also very useful for after the jam when you want to go revisit an awesome game you remember playing!