So I can now register with this board AND have a topic where I contribute effectively? This is my day...
VTT are really the only way I can still play PnP RPG's these days with all my friends living across the states. It's not the best, as nothing I think ever will replace in person, but there are some nice advantages that come with using a computer rather than that usual dry-erase board.
Some of things I enjoy are the ability to handle all the rolling, monster stat tracking (i.e. HP's), sweet looking maps to play on, and with some time spent preparing, you really can plow through a ton of material.
The biggest thing I have a hard time with, is keeping action so quick paced that people stay interested. The thing is that your sitting in front of the same computer that you play super awesome video games with, only now you are using to play a game that is over 25 years old. People always seem to drift off since they expect this magic box to show them pretty things and most VTT don't automate crap (they really just act as a super powerful resource tracker). It just means you need to have a DM that is really prepared with context lines and good maps.
That being said, to keep things short, if you want to look into VTT's that are worth a shit, look at the following ...
1.
www.d20pro.com-> Amazing for 3.5 framework, CRAP for anything else. Spent countless hours using this.
2.
www.rptools.net-> Since you basically have to program it yourself, it can be great for any rule system...as long as you program it that way. I use this a lot for anything not DnD related.
3.
www.roll20.net-> Very lite and easy to use. Not much meat and potato to it but it's still being developed. I"m following this because it shows promise.
4.
www.fantasygrounds.com-> Its old, not very easy to use, but it can be great. I used to use this a while back but not any more since the above mentioned.