VNC Viewer with clipboard sync
Jollys Fast VNC

It attempts to keep the clipboards in sync and for the most part it does a very good job of it. Not all objects copied to the clipboard on one machine can be used on another though. For example: copying a file the clipboard just puts a lean file object in the clipboard which has no parallel on the remote machine.

But for text and such it works great.

There's a free trial (that continually renews itself) and you can buy it in the MAS as well for not a lot of money (there's a "home" version for even less).