I have started a full walkthrough/game guide for Lego Batman over here: http://www.giantbomb.com/guides/lego-batman-game-guide/899/
It is very bare at the minute, but it is intended as a collaborative effort with the community. GiantBomb have made some great tools here, so let's try and get some use out of them!

If you have the time feel free to write a walkthrough for a level or fill out some of the missing details.