Over the past year or so I've really gotten into modding as well as trying out various fan made games on PC. There is some really cool stuff out there if you're willing to take the time to look for it. For example, there are many Mega Man fan games such as Mega Man Rock Force, Mega Man Eternal, and Mega Man Unlimited. For the Sonic fans out there, there's Sonic Before the Sequel and Sonic After the Sequel, both of which are very well made.
As far as modding goes, Doom is one of the easiest games to mod and there are a ton of custom levels to try out. I'm currently looking in to modding Sonic Generations for custom skins and levels. Fans have actually recreated the daytime stages of Sonic Unleashed and put them into a mod for Sonic Generations, which is really neat.
So is anyone else interested in this type of stuff? I know not everyone has access to a great PC, but some of these projects are still worth checking out.