It is the new practice of putting applications that the system thinks you use into memory whenever it can. Just because a program is in memory doesn't mean it's "running" and just because a program that's not running is in memory doesn't mean it's taking up any free/available resources, since if it's not running and if someone needs the space it will just overwrite that area. The advantages far outweighs the small startup cost of putting it in there at start to begin with, since if you ever want to run that app it'll already be in memory.(this is under the assumption you will likely run the app again) Same thing occurs on your desktop these days which try to predict which applications you use most and try to fill up as much memory as possible... Don't know why people keep complaining about this... it's a GOOD thing. You should be questioning it when it doesn't do this.
As for crap that "is" running w/o your know how that are not system services, well... read the info on the apps you install, it tells you if it's doing all kinds of stupid stuff since you have to click install on that message page. So if you installed a Tic-Tac-Toe game and its accessing your gps, wifi, phone, sms and what have you and in the background... don't complain your gps and a whole bunch of stuff are running.