Someone who is very good at doing a variety of useful things.
Justin and Sean would be the JACKS-OF-ALL-TRADES up in hurr.
someone who is skilled at a great deal of tasks, usually in the same feild, but who lacks suffcient skill in any one specific area.
"He can play guitar, keys and drums, but he just isn't that great"
"Jack-of-all-trades master of none"