Isn't it nice when you post. And people post. And you post. yay.
One thing that I absolutely love is having the opportunity to actually coordinate with someone to cooperatively write a scene.
Look, I know this doesn't happen very often for some reason. The easiest way to RP via a forum is to just take turns writing your scenes out. This works great for certain kinds of roleplays - nation roleplays, for instance - but not so well for others. It's those others that seem to hurt from the nature of forum RP. Simple conversations can turn into long paragraphs of nothing happening; action scenes can become a sort of competition to see who can write the bestest and meanester. Etc.
But when you shoot PMs back and forth with someone to handle a conversation, or when you use a chatroom or Google document to write out and edit your work together, there's this awesome since of "Holy crap, this is looking like a scene from a BOOK!" Paragraphs of nothing turn into witty discourse, back-and-forth snapping and comedy gold. Action scenes actually get the speed they need to feel like action scenes: one character swings, the other parries, and then his foot is kicked out from underneath him, and on and on the fight goes. It flows so much better, reads so much better...
And in the short time I've had this account, I'd had the opportunity to collaborate on a neat dialogue scene with someone, I've discussed future collaborations with others, and I've had pleasant conversations with players whose characters were going to be at odds with mine... It's a good feeling. I don't know if I'll have a lot more collaborative works while I'm on this site, but I hope I do.
Also, I just want to say that it's nice to be able to join roleplays that let me post at a pace that's... well, more my own. I'm a busy student, and I can't always post at the same rate as everyone else. In the past, I've lost friends over my busy schedule: people I played tabletop games with, people I roleplayed on WoW with... Some folks I played with just couldn't accept that my schedule was unpredictable, that I'd have to skip some game sessions, that I'd have to reschedule things to study more, or that, yeah, I sometimes forget I have an assignment due until the last minute and so have to stop whatever I'm doing and get that assignment done.
But thus far, I've had great experiences on the forum and great leniency concerning my timetable. Folks don't mind that I expect to only be able to post <X> times per week. I haven't been throttled for posting something a day after I said I'd have it done. There's a lot of understanding in general. I'm happy about that.
I love video games, but they all have set mechanics and methods that you have to use. You're restricted to the controls and abilities the game gives you.
The fact that RPs are creative enough to allow you to get away with saying "Let's use this glove of pickpocketing to scale a cliff" and "My character is a bear that pretends to speak English through bluffing" makes me so happy.