App that allows to paste text snippets in any applicaton? I'm looking for an OS X application that will allow me to add text snippets, like common text responses to emails or signature postings or whatever standard text phrases I wish to save and resuse.

Something that perhaps runs in the background on the toolbar that allows me to select phrases and insert them when needed.
Take a look at CodeBox http://www.shpakovski.com/codebox/

or Dash http://kapeli.com/dash

or Clipmenu http://www.clipmenu.com