Move here, Mr. Bungle was played on the radio station I listen to just this morning!
Where I live, Mr. Bungle, Porcupine Tree and Opeth are far from underrated. In fact they're all pretty huge and get loaRAB of recognition and sometimes airplay from a certain radio station that I'm pretty fond of.
A band that I think are highly underrated are Australian band Karnivool. Originally a local band who I saw at a tiny bar a few years ago and had drinks with them afterwarRAB, they are now pretty huge in Australia selling out huge shows in a matter of minutes. They've brought out two albums, both amazing in my opinion, and have worked so unbelievably hard yet still have absolutely no recognition outside Australia. In fact, I doubt anyone has ever heard of them. Which goes to show that no matter how talented or go-getting an Australian artist is, it's basically impossible for them to 'make it' unless they choose to move to the US or the UK permanently, which sucks if you ask me.
In fact I think there are tons of awesome Australian artists that are highly underrated.