Not sure whats so secret but, here's whats I have installed / use:-
AlienSkin Exposure 2 - Film stock emulation
Alien Skin Image Doctor 2 -Image repair / restoration
Alien Skin Impact 5.2 - I use this mostly for perspective shadows (but you always need to tweak them after)
Alien Skin Blow-Up - Making small images bigger
AV Bros. Page Curl Pro - Page curls and folds
Digital Film Tools Light 3.5 - Lighting effects
Knoll Light Factory 2.5 - Lens flares
After Effects :-
Trapcode Shine - Shiny effects
Trapcode Particular - Sparks / rain / fog / clouds
Trapcode Form - Lighty plasma type effects
Trapcode Starglow - to add sparles
Most plug-in's are simply great timesavers and I use elements of all of them everyday both professionally at work and for hobbies including making cover, along with other programs including Cinema 4D 10.5, Bodypaint 3, Maya, 3D Studio Max 9, Illustrator CS3, Corel Painter X, Softimage XSI and ZBrush 3. Bear in mind though you still need to now how and more importantly when to use them all otherwise you wind up with a mess just the same.
Hope it helps you.