Brolin was good in the Coen Bros' remake of True Grit too. He is a talented guy, it will be interesting to see where he goes from here.
I've had my eye on Ryan Gosling since he did Drive and Ides Of March. I don't know though, he's iffy. Good potential though. Speaking of Ides Of March, I wish more people would notice how fucking awesome Philip Seymour Hoffman is, though he is pretty sucessful overall. I still feel not that many people know how awesome he is. While I'm on that movie I will say that I think Clooney has come into his own in his later years in a big way. Obviously he is also a very well known actor and might not qualify as underrated, but it definitely depends on who you ask, a lot of people seem to hate him, lol.
Let's see, actually underrated actors... I was just in the netflix thread and I mentioned I've been watching a lot of Matthew Broderick movies. (Watching Godzilla right now!) I feel he qualifies as underrated even though he's really well known. He really bombed in the 90's-00's but has been making new stuff lately that I feel has a lot of meaning and depth to it... and the early stuff from the 80's is quality, as everyone knows.
Shiiiit who else... there are a lot of underrated actors but unfortunately their under-casting tends to make them hard to think of, LOL. How appropriate.
I don't know, there are a LOT of actors that I feel are underrated but still have a lot of notoriety and are well known, like Broderick. Alan Alda has done some interesting stuff later in life. A lot of actors kind of fall off radar later in life after their first big bout of success... but sometimes they come resurfacing like a tiger, haha. And some fall right off the fucking boat and drown. (Adam Sandler...)
I'm a wicked movie buff... love this shit.
I'm a big fan of Jon Krasinski, the guy that played Jim on The Office. I don't know if he qualifies as underrated because obviously he was massively successful and loved as Jim, but I do feel that he has struggled in the movie industry and hasn't really become a well known name in cinema despite his efforts, which tend to kind of fall by the wayside and not quite make it to the A-List even though they're pretty solid.
Same can be said about a lot of other television actors who struggle to break into big film... pigeonholing is an ugly thing unfortunately... a lot of Star Trek TNG's actors were broadway quality, but you don't see them in much after the series because they were solidly pigeonholed. Exception being Patrick Stewart, who I fuckin' love, and certainly is a well known name, but I do feel that most people don't appreciate his acting ability, he's a very talented dude.