If there is something to be known about me, its that I friggin love chiptunes (well that and I have like 10 squirrel brains in place of a human brain).
Sources of stuff:
http://www.youtube.com/otobeya - This guy makes chiptunes based on other music. Lately he's taken to making chiptunes of anime openings.
http://www.youtube.com/grad1u5 - Lots of uploads of video game music.
Some examples:
http://www.youtube.com/watch?v=sjjZId6mZLw - I don't know anything of either the Jam Project or Super Robot Wars. I do know that this is awesome.
http://www.youtube.com/watch?v=swl0Zc6IK9I - Doooooooooooodge! Otobeya actually has a huge medley of Gradius music somewhere on his homepage.
http://www.youtube.com/watch?v=Cdn7QMtPaDs - Cute!
http://www.youtube.com/watch?v=bOgBb8h7LHw - My GOD is that an awesome transformation. A quaint little tune becomes an epic.
http://www.youtube.com/watch?v=qE9JEnNGnV4 - The stage 2 theme is the best. Natsume produced some head knockin' stuff back in the day. Shadow of the Ninja, Shatterhand, Abadox, and S.C.A.T. all had awesome music.
And now they just make Harvest Moon.
http://www.youtube.com/watch?v=N-B7BChD-M8 - Maybe I'm weird, but I think the first song is pretty.
http://www.youtube.com/watch?v=QbfKTrt29Tw - 1943 was my first shmup ever. I like the stage 2 and 3 themes, they have an old fashioned feel.
Post your favorites if you fancy!