What is a Photoshop plug-in? Name few of them that you use more and found interesting for sharing with us?

are add-on programs aimed at providing additional image effects or performing tasks that are impossible or hard to fulfill using Adobe Photoshop alone.
Plugins can be opened from within Photoshop and several other image editing programs (compatible with the appropriate Adobe specifications) and act like mini-editors that modify the image.
like Alien Skin Eye Candy5 AlphaPlugins Engraver Auto Fx DreamSuite Series Flaming Pear SuperBladePro

I don't use any now ...
but befor i used to use Eye Candy