yeah that's what this thread is about. my favorites are

macross plus
INFORMATION HIGH - Macross Plus OST - YouTube

eureka seven
Eureka seveN - Storywriter - YouTube

gurren lagann
http://www.youtube.com/watch?v=QVb8nKj6iYo

gundam unicorn
Gundam Unicorn OST | Track 2 | Unicorn

i think my enjoyment of the genre started with this though:

general daimos
General Daimos - YouTube

if bleys was here he'd start talking about gundams and char and everyone would sigh and leave the thread. what's your favorite mecha? what's your favorite mecha show?