Have you ever done a Play by Post RPG? I'm very curious about them. Through my search I have found several different types of formats to run these games. I do not have any experience, but just want to write about where my search has led me.
The first and most involved type is where the forum is a whole world. An example of this is Mizahar. I actually found this one back in October or so. I was fastinated with the world and spent hours reading posts and getting a feel for what what going on. I did end up creating a character sheet and being approved to play. In the end though I just couldn't put anything in print. A lot of the players were really posting solo or with 1 other person involved. I couldn't think of where to start, even though I have this whole life for that girl in my head. I have found a many of other websites like that. Spirits of the Earth and Disney World of War are a couple. Be prepared to do a lot of writing on these kinds of forums.
Next I found one that was basically one continuous story, the posts just went in the order of time they are posted, Ongoing Worlds. I like this site because I can read the stories without having to sign up for the games. There are a variety of games created here, horror, sci-fi, fantasy. Go have a look and join in on one.
I have settled on trying a game at RolePlay onLine. It is a site where you can run any kind of game you like. Once you start a game you basically get your own forum play in. You can run games that need die rolls or just story playing.
I joined Savage Worlds 4400. I know how to play Savage Worlds and I know the show 4400.. so I had to sign up!
Finding the right game to play at the right site will take some time since there are 1000's of games open at any time. If you are interested in trying a Play by Post game just keep looking until you find one that fits your style.
If playing with the group at a specific time suits you more, try Roll 20, where the site is set up for virtual table tops. Find a game that fits your time schedule and sign up!