Shea Lignitz reviewedPaste 2Smart cloud clipboard history and snippets manager for Mac
 Recommended
Pros: 

Great for storing things you only need for a short while and things you'll need longterm.

Cons: 

I haven't found a better alternative.

Really relieves the headache of going back and forth between tabs and windows copying and pasting one thing at a time. Copy images, plain text, links, etc. You can even tell it what kinds of things you don't want copied (e.g., passwords, etc.).