Sonitus:FX Suite
Cakewalk bought this effects suite and began including it bundled with their Sonar product lines. I have A/B'ed these effects with their much more expensive counterparts, made by Steinberg, Waves, and other flagship companies, and saw absolutely no compelling reason to pay extra money when I get such top notch equalizers, limiters, and other effects for free with Sonar. Yes, they are that good! Believe it!

Sony Sound Forge Effects Plugins
Sound Forge is my current "destructive" sample editor of choice. Of course, with any good sample editor comes a collection of DirectX effects that can be used in any other application which supports it. Sony has included some very interesting and useful effects with Sound Forge. Although I think the Sonitus compressors and equalizers have a more natural sound, Sony brings up the "loudness maximizer" to truly mash all the dynamics out of a sample if you just need a really loud or punchy drum sample (for example). There are a quite a few gems in this collection.

Cakewalk Project 5 Effects Plugins
Out of all the effects packages I own, this collection is my favorite. The interface is very natural, uses very little screen real estate, always easily syncs to tempo with the click of a mouse, and sounds absolutely amazing. I loved the instruments and effects that came with Project 5 so much, I bought it JUST for them. I really don't care for the new fangled sequencing interface compared to Sonar. But the plugins were too good to pass up!

Sonar includes several other effects processors (that I have not familiarized myself with much yet). I also use a wide array of freeware VST and DirectX effects I have picked up over the years, each bringing something very unique to the table, and I will also post about them in the future.