I have a 30 team dynasty league that mimics a real-life GM experience. The league began last winter with each GM choosing a MLB team and using that roster (including minor leagues) to build a competitive fantasy team. People traded, signed free agents to short and long term (up to 4 years) contracts, etc.
Most of the real hot stove activity happens during the offseason, so naturally the regular season is a little bit slower. We did have a lot of activity at the trade deadline though, and things are going strong. Unfortunately, we have lost some of our less patient GMs. Some of their teams are actually having good seasons, while others are struggling a bit. Meanwhile, some of them have very bright futures, but again, others not so much. Depending on whether you want a team that's built to win now, a team that's built for the future, or a team that's going to be a major reclamation project, we have teams that may fit your needs.
Our league headquarters is on a site called Proboards, while our baseball is played on Yahoo in three separate leagues (an AL, NL, and a playoff league).
Starting next week, we have our amateur draft. The draft starts Tuesday and will likely take a few weeks. It lasts six rounds and a compensation round. Any player drafted in the 2011 June Draft is eligible for our draft, as are any minor leaguers not already on someone's roster. One of the available teams has the third pick in the draft.
If you are interested in taking over a team, send an email to firstname.lastname@example.org. The reason I ask for patient GMs is that things may be slow at first, but they will pick up, particularly with the trade deadline approaching. And during the offseason, there will be plenty of activity to look forward to.
It's a fun format and we're working hard to keep the league going strong, so send me an email if you want to be a part of that.