I'm involved in two campaigns right now. One is based on Tolkien's First Age histories, and the other is a homemade campaign setting.
The first one is very interesting because the DM weaves our characters into the established plot, but let's us explore other venues. In that campaign, I play a 9th level Ranger (Rohirrim) called Alastriona (al-AS-TRI-na). She has lost her village, fought her brother (at the time she was level 5, he was level 12. I have no idea how I held him off) due to his madness/possession by Sauron, and developed a relationship with Curufin. Yes we are nerds.
In the latter campaign, I play a character who is actually three separate people imbued into one. The character has physical attributes of all three people, and the minds of the three struggle for control. Each time the character wakes up from sleep or unconciousness, we roll a percentage (based on the spiritual dominance of each character) to determine which persona the character has. The character is comprised of a quarter silver dragonian swashbuckler, a drow cleric and a human monk. The drow, obviously, is an evil character, while the swashbuckler is neutral/good and the monk lawful good. Each character has a similar goal, but a different purpose and way of reaching that goal. It is very interesting. Unfortunately, I haven't much used the cleric in battle. It's disappointing because I've never played a magic user before, and still haven't gotten to experience it.
We play a homebrew of 3 and 3.5, using the rules that make the most sense.