Shin Okada
Explorer
I have never done this kind of thing. And will never do it.
The main reason is that it may spoil the fun of the gaming session if a DM tries to judge what kind of role-playing or background-story is "good" or "bad". Every player has their own tastes. Also, some players are good at making and writing up story, others are good at making strategy, yet others are good at painting miniatures, etc. I will not try to reward someone with particular talent when the entire play group is just having fun. Because that is the most important thing.
And, as already pointed-out by Runestar, in 3.5e (or 3.0e with FR rules), a lower-level character gets more XPs from an encounter. So one-time XP reward for particular member is often not so meaningful.
The main reason is that it may spoil the fun of the gaming session if a DM tries to judge what kind of role-playing or background-story is "good" or "bad". Every player has their own tastes. Also, some players are good at making and writing up story, others are good at making strategy, yet others are good at painting miniatures, etc. I will not try to reward someone with particular talent when the entire play group is just having fun. Because that is the most important thing.
And, as already pointed-out by Runestar, in 3.5e (or 3.0e with FR rules), a lower-level character gets more XPs from an encounter. So one-time XP reward for particular member is often not so meaningful.