The thing about online descriptions and personalities is that they can be completely constructed. Gender means relatively little in relation to the person in real life, although it has been noted that even online, women get a lot more attention from men than vice versa. Or rather, I should say that female characters get a lot more attention than male characters do, for there is really no way to check on these things, nor is it really important. In fact, gender online can pretty much be ignored, if wanted.
There is also much more of an emphasis put on the actual doing of actions in a MOO, since the characters are actually interacting in an environment. And while certain things, such as proximity, are put aside, there is still a great deal of social interaction that can take place.