Ok here’s my primary option. I tend to wax a little eloquent so I’ll make a real effort to keep it brief. :P (Guess I made a bit of a mockery of the brevity...)
Bethany is a female troll who was a member of a happy and relatively well off corp family until the age of nine when she underwent genetic expression. Her family knew that a troll child was going to be unacceptable to their parent corp and chose to abandon the child. They still had loving happy memories of their daughter-that-was, so they talked to someone-who-knew-a-guy-who-could-talk-to-someone, and found a foster home for her in a part of town that looked upon trolls with a little more acceptance.
The foster family took the money that was offered for her care but didn’t treat Beth very well at all. She was treated as a third class family member and forced to assist with the foster family’s income by performing menial labour. She was regularly smacked about, told how worthless she was, had food withheld, was forced to sleep in the laundry or kitchen, and was pretty much treated as the house slave.
After about a year of this she came to the realisation that as a ten year old troll, female or not, she was actually physically stronger than anyone else in the family. Quickly following on from this realisation was one that she didn’t have to put up with her beatings any more.
One night her drunken foster father, on returning home from the pub, suggested she cook him some eggs. She told him maybe he would like to cook his own eggs (or words to that effect), and the resulting altercation left him with a broken jaw and a few cracked ribs. It left Beth with a new-found respect for her own ability to look after herself, but unfortunately (or not), without a place to call home.
Life on the streets of the Seattle Barrens (or somewhere more appropriate to the campaign) was rough, but while the new Beth was pretty ugly, she was most certainly not stupid. She quickly learned the basics of life on the streets. How to spot a sympathetic mark, which gangs to steer clear of, who controlled what areas and how tetchy they were about trespassing trolls. She also developed a strong sense of sympathy for anyone in a hard spot, and as she got to know her community, she came to care and look after the people even less fortunate than her. She found a mentor in a local street doc who had a similar sentiment and provided care to the needy of the neighborhood. She would help him on his rounds and he taught her basic healthcare in return for her much appreciated assistance.
The doc also helped her through a rough patch when she started having particularly vivid dreams and sometimes even waking hallucinations. She was terrified she was losing her mind, but with a bit of patience and some clever testing, the doc had some more interesting news for her. Not only was she a troll, but she was also a recently awakened troll! Unfortunately it seemed that the development of magical awareness came with a price for Beth. She had almost overnight, developed a severe allergy to soy, which made for a pretty unpleasant complication in her diet. Luckily for her, a trollish constitution allowed for the consumption of many things that other people might not even be able to look at.
Beth was not particularly fussed about this new development. Her doc said she was a mage, but what good was that if she didn't know how to do anything with her new abilities? Doc was insistent that this would change Beth's life and could be exactly what she needed to pull her up out of the life of hardship that everyone else in her community was forced to live by circumstance. Beth wasn't so sure she wanted to be pulled up out of this life of hardship. She was getting by just fine and had found a place in the world where she was appreciated and wanted. Whatever the case, doc was able to pull some favours and Beth agreed to at least some very (very) basic training in the use of the mystical arts.
And a taste was all Beth needed to make her realise how much more she could do for her community with more knowledge of how to use her magic. She couldn't afford any tutoring, but she hungrily devoured any material she could get her hands on, and slowly but surely she was able to develop her skills.
Skip forward a bit and you'll find an older, more cynical Beth. She's 18 now, still living in the same community, helping doc with his rounds. Her magical skills have come a long way, but are far from fully realised. Her allergy has helped keep the rat population down. She's made lots of friends in the community, and lost many as well. She's seen a lot of the worst of what goes on in the sprawl. Pulled bullets out of friends, held their guts in while they have cried and died. Seen death by gunfire, disease, double-cross, starvation, exposure, you name it. She doesn't believe there is a lot of goodness left in the world these days, but she'll be damned if she doesn't do what she can to make life a little more bearable for her friends. And lately she has found another way to make a bit of extra nuyen. It seems that in the shadows, once word gets out that you're a mage, the work comes to you...
I can't upload the file here. Invalid file type. Without the sheet to tee up the skills with the background it's just a sad little story, but oh well. Hopefully it has a happy ending.

I used the SR4CharGen prog that Mongrel linked to earlier. Chris if you give me an address or somewhere you'd like me to upload it I can do that. She's all legal SR4 standard rules. If we end up with more or less build points I can modify accordingly and if she just doesn't fit in, like I said I have plenty more options.