May as well stick my Top 5 in... Even if I can't think of just five I like most in particular... xD (And there will be some Hatsune Miku tracks... xD Otherwise this would be VERY difficult to fill...)
1. Hatsune Miku Project Diva f - Monochrome ∞ Blue Sky
2. Sonic '06/Next Gen - Dreams of an Absolution
3. Sonic Shuffle - Steal Ship
4. Hatsune Miku Project Diva f - Remote Control
5. Sonic Shuffle - Wake Up One
(Actually, thinking about it, this list could have easily been just Sonic Shuffle tracks... xD)