One of the things that I think a lot of online chat based RPGs have over their table top cousins is that you can get a very real sense of who a person is in the chat game a lot easier. Part of the reason for this is the anonymity and isolation of a single user at their computer playing the character. Distractions have a harder time impacting the game. There is more too though. It's something I've tried to capture in my games of late. I've had varied results, but here are some of the things that have come up.
In the last session of my Shadowrun game one of the PCs decided to move house. Now the game started off with everyone living in the same mega housing block so this is literally a PC leaving the roost from the beginning of the game. The reasons for the move are all IC. In the beginning I got the character into Shadowrunning by killing their grandfather/legal guardian and, essentially, there's just a lot of memories in the old apartment that the character wants to get away from. This makes it a significant event - a "growing up" type thing - for the character. It is also an opportunity for me in running the game.
How so? Well, with the character living somewhere else it means I can contrast the new place to the old one. Differences in the land lord, differences in the fellow people that live in the same area. I can also do differences in the area and the people that live around there. Essentially, I get to give more character to my setting and to the Shadowrun world. Hopefully it'll play off nicely.
Quiet Moments = Real People
This is personal preference, but I rather enjoy on occasion having sessions where effectively nothing happens. It's down time. Time for time to pass by and for the characters to take care of their personal things. This can lead to things you wouldn't expect - like a player wanting to move house - and it can let the players really feel their character by experiencing them not just on the job but also in the quiet moments that go on between them. Ever have a character that likes to spin techno discs in his quiet time? How about someone working on a dissertation for their PhD? Working on growing their own vegetables? I've got all of these in my current Shadowrun game, and while individually they may not be special it is a cool thing that really can only happen when your players get a chance - or make the chance - to focus on who their character is aside from stats that can dispense death, complete jobs, and make money for gear.
Friends = Contacts
This is one that is built into Shadowrun, but all the people that the PCs meet during sessions? They can be contacted and used for information later. Those contacts the characters already have? May end up too busy to help the PC out if they are not kept in touch with for a long enough time. This is an old mechanic in Shadowrun, but it is also an awesome one. For one, it makes players think of NPCs as more than just NPCs and it gives the player a reason to consider who their character is and how they know that person. After all when the game tells you that your blood thirsty troll street sammy likely won't stay friends with the pacifist street doc for long unless they have a damn good reason to do so. Even then, once whatever obligation is paid? Unlikely.
The quiet sessions I was talking about above also give the player time to maintain these contacts and how they do it can be just as awesome. I've got a player in my game kind of dating a married Orc street-doc/nurse NPC in an open relationship. I've got another player going off for street races on a regular basis, the races being run by their contact. A third player keeps his contacts primarily professional, but he also makes sure to cut them in whenever he can on a deal.