One of my lectures finished early and instead of sticking around for Q&A I decided to duck into a neighboring session that was still in progress, which turned out to be the COO of Cryptic Studios, Craig Zinkievich, talking about how they leveraged user generated content (UGC) for Neverwinter and Star Trek Online. Even though I only caught the tail end of the talk I pulled a couple of nuggets of information out of it.
Obviously the first step that should be taken is providing the user base with decent tools. I'm sure Craig expanded on this earlier in the talk but we can fill in a lot with common sense: make them accessible, intuitive, and basic. Unfortunately I wasn't around to hear how much extra effort the team put into these tools - whether they were built specifically for the players or simply polished up versions of the developer tools. Either way you should decide very early on in development whether or not you want to be supporting UGC for your game.
When it comes down to learning how to use these tools, even ones that aren't designed to be used by outside parties, Cryptic has found the community to be largely self-sufficient. This makes sense, as you have to remember a large portion of games that don't support mods end up having them anyways - a lot of your players are very smart and a good portion of them are very generous too, setting up websites and wikis to help inform other people through written tutorials or videos on how to use the game's tool set. Craig admitted with no shame that he and the team feel the players do a better job of documenting the tools than the dev team does. So be ready to offer assistance, but keep an eye on the community to keep your dev team from wasting hours on docs that have already been produced.
With any game, the amount of UGC is always going to start out very small, with a few authors willing to take on the challenge of learning the tool set and providing extra content for other players to enjoy. If you don't make this content easily visible to the rest of the community this spark will quickly fizzle and die as more people are willing to produce UGC for recognition than they are strictly for themselves. Or rather, those that produce the UGC for themselves won't bother attempting to share it if doing so doesn't get them any recognition. For STO, Cryptic has numerous built-in portals within the game and the website that displays highlighted UGC to make it easy for players to find and download new content.
It's important to realize that the majority of UGC will not be good, and even less will be close to the original development team's standards (although this also depends on how powerful the tools are that are provided to the community). Finding the good UGC to deliver to the player base was easy enough - Cryptic implemented a simple 5-star rating system for players to use once they had checked out the UGC. The participation of the players in this voting helped them to realize that of the 50,000 hours of additional content added to the game by the players, 200 or so was actually of decent quality.
Still, that's 200 hours of gameplay the actual development team didn't have to spend time creating to keep the players occupied as the product remained active on the market months after release (about 22-23% of players are taking regular advantage of extra UGC). Instead the dev team got to focus on new in-house additional content as well as fixing bugs and resolving issues with the gameplay - plenty of which turned up as people tried to get the game to work a certain way when creating their own content.
Once your UGC base has grown to a size that begins to have an effect on your community, with people playing and creating content on a regular basis, you may feel the urge to try and perhaps maybe sort of... monetize it a little bit. Charge a few bucks for better tools or for uploading content to a premium portal. Craig emphasized that under no circumstances is this a ever good idea. Just don't do it. Remember what you're already getting out of the UGC in extra player hours. On the flip-side, you may consider trying to entice players to develop UGC by having a way for them to earn money creating content. Cryptic has stayed away from this approach so far due to the financial and legal issues involved, however Craig stated that they are keeping a very close eye on Diablo III's real money market and is wondering if Blizzard will succeed in breaking new ground in this area.