The toweringly awesome Alfred 2 app for OS X has a great clipboard history browser. This is how I suggest you configure and use it:
- Map a hotkey to the viewer (I suggest making it something involving the letter V, since Cmd-V is a normal Paste. I use Cmd-Shift-Option-Ctrl V because I have my Caps Lock key mapped to Cmd-Shift-Option-Ctrl)
- Turn off the option to show snippets at the top of the Clipboard History, because snippets are a whole different thing and not relevant to pasting history
- Turn on the option to auto-paste when you hit Enter on a given item
With these options all configured, all you have to do is hit the hotkey, select the old clipboard item you want and hit Enter. It will then be pasted into the active window.
This is also useful to preview the current contents of the clipboard before pasting (which is always a good idea if you're pasting into a sensitive terminal or a work IRC channel and want to avoid spamming some random/harmful nonsense in).