There are many operations to speed up your mac as did to my insanely fast powerbook!
(yes i have a powerbook G4, stop laughing intel mac users)
1. Try your best to remove applications you don't usually use (more hd available, the more space your ram has for process transfers) ex. i don't use garageband
2.Try to leave little files or folders in your desktop as possible ( this will significantly decrease your boot time)
3. Try using Onyx or other maintenence apps to handle permission repair, scripts etc.
Thats so far what I'll recommend if you want to decrease boot time as well as improve your macs performance.
PS, try to max out your ram your machine can handle; you can never get enough ram
Hope this helps (MidgetSanchez)
If you have any other questions feel free to ask.
My Boot time:15 Seconds
Cheers