Les,
This is a pretty popular topic, My list is somewhere in the archives, but here goes again:
Joe’s filters
Eureka!
Gfilters- all
G film
Continuum Complete
TMTC
Telly’s filters
CHV – all
Silhouette Roto
DVmatte Pro
ReelSmart Motion Blur
PanZoom Pro- for Ken Burns effects, absolutely the best.
With all the above, I hardly ever have to leave FCP.
For Motion, DVmatte Blast for keying, will blow you away.