Are you actually joking? I've yet to meet someone IRL that doesn't think he's a complete douchebag but i can't wait till I do so I can make fun of them.
Pretty much totally agree with OP's list, except MSP isn't overrated because they are legit and their movies generally have a bit of everything and some seriously gnarley like "ima die" kind of shit.
Also Party Down isn't underrated because its pretty meh, and Kenny Powers isn't underrated because everyone I know who watches HBO thinks its one of the best shows on tv right now, which it totally is. So it is correctly rated high.
Also Mars Volta is overrated if anything, only their first cd was any good. And when you say Australian hip-hop, I'm interested who you are referring to. Lyrical Commission are completely ace and I love them, but I haven't heard much else come out of Australia other than their EP and solo EP's from members of that group.