Not sure if this is what you're looking for, but well, there's a whole lot of stuff...let's just start with the REALLY overly used ones:
Boyfriend/girlfriend breaking up
Peer pressure to do drugs, drink and the like (usually followed by giving in and getting in trouble or not giving in and made fun by friends)
Being invited or not to a popular crowd party
Family embarrasing or not allowing him/her to do something (such as going to a concert or party)
Friends back stabbing
Romance problems (example: Amy likes Jaron but Jaron likes her best friend Sarah while Sarah has a boyfriend Eric who is enemies with Jimmy who likes Amy)
Being grounded or privilages taken away
And...you get the idea
