Anyone (preferably after doing a few playthroughs) used the Burger mod yet? You just replace one file and it's installed. Restore it and it's back to normal.
It's very well done, just pause the game and you get a new Debug menu item, you can max out health, invicibiltity, the usual stuff, but what I like is the shop, just add a couple of praxis, a weapons mod or some ammo. Only limit is your current inventory. I've been opening old saves and reliving parts (like taking out every copper in the police station with the laser and the see-through-walls aug).
You can start the game with all augs if that floats your boat..
You can add stuff like the VIP card for the Hive, achievements etc. Very nice to add some replay fun to the game. It'll do while I wait to buy the new DLC.
I've been playing with maxed out batteries (they never run out), arkham asylum style, look through walls with silent running and never ending invisibility.
Here's a demo [probable spoilers]:
and here's the thing:
http://forums.eidosgames.com/showthread.php?t=121245
(doesn't work with new DLC).