Native Plugs:
1.) EXS24 - Intuitive, efficient. Can garner amazing results with almost any type of instrument. I primarily use it for drums.
2.) Channel EQ - On every track, almost.
3.) Pitch Shifter II - while not the best pitch shifting algorithms, I am very fond of the adjustable "colour" parameter.
4.) Space Designer - Use it on the hats, some mid range instruments, etc. Expansive reverb options with quality results.
Third Party:
1.) Absynth 3 - The sickest synth plug ever. Not only for its already expansive and tight preset library, but the programming interface is great and nicely designed. Great relationship between program and user through the GUI.
2.) PSP Vintage Warmer - Tight final limiter for the bounced mix.