well...I dont want to mostly make walkthroughs for flash games, but if you have played Bio Shock then you know it is like a maze.
For the most part the map for the game does not help, and with help i think I could make one for it in a few weeks at most.
This site is centered around flash games, so posting walk-throughs for other games here would be somewhat pointless. Though there are many site out there you can submit game walk-throughs to if you have them.
Hunt around the puzzle and RPG games. I can't think of any right now. The most common and best games to write walk-throughs for would be games like godlimation's 'Trapped' series. But he has already written walk-throughs for all of them and there is only one or so others like it, and they already have walk-throughs. You'll just have to watch out for them.