Ok, so I started playing around with the left4dead developer tools this weekend, specifically the map maker. Amazingly enough, my experience with mapping for quake 3 is actually still applicable to some degree. Don't expect anything from me any time soon, but I'm definitely feeling a bit of that mapping urge.

Anyway, for anyone interested, it's really not that hard. I haven't delved into custom models or textures yet... I'm not sure how difficult that would be to implement.

If you're interested at all, these tutorials got me started
http://developer.valvesoftware.com/wiki ... l_Creation

I doubt I'll be making full maps, but I think I will fiddle around a bit with the parameters. Good luck with the mapping - interested to see what your twisted mind comes up with it.