It's hard to take a middle road with this stuff. My kids (already in their mid to late 20's) were probably electronically deprived a bit, but very savvy with the computer, despite that. I think it's oK for middle school kids to have phones and access to a computer at home. MP3 players, well, as stated before, there are cheap ones.
But, I am not sure if 12 year olds (I have many many years experience teaching this age group) would react well to the "giving" idea. Kids this age do like getting involved in community service, but I think you would need to be sure that these girls are "into" this. Otherwise, it might make things difficult for the birthday girl, back at school the next day. Girls this age prey on "differentness" and while it is a not very nice part of middle school, it is something a parent has to be aware of. This comes from a parent who encouraged these things and had one kid who started an environmental club in 5th grade and actually helped the town start a recycling program. But... just a warning about how other kids could perceive these types of activities. It has to come from within and from the home.