The ability to copy and paste text is a staple of the modern OS. Even iOS can do it, but on the Mac, the default clipboard behavior can be a bit limiting at times.
CmdVees is a US$4.99 ($0.99 when reviewed) Mac App Store utility that acts as an extension to the OS X clipboard, allowing sequential clippings instead of forcing one copy to overwrite the next. Say you want to copy three things from one app to another separately -- with the default Mac clipboard behavior, you'd have to swop between those two apps three separate times (once for each piece of text you want to copy over). CmdVees allows you to copy the three pieces of text sequentially, one after the other, and then paste those clippings back in the order that you copied them, or combine them into one clipping.
Once each clipping has been pasted via Cmd+V, it's removed from the CmdVees clipboard, making it a quick, one-time copy and paste enhancement, which allows for rapid re-arrangement of text among many other previously tedious activities. If you need something else, including multiple pastes from one clipping, you can use Cmd+Shift+V or activate it from the CmdVees menu bar app, which allows you to see everything on your clipboard, the shortcuts for various functions, and pasting of items via a single click. You can also tell CmdVees to strip out formatting from text, which is incredibly handy if you happen to write for a living.
We've previously covered another $0.99 tool from the MAS for similar uses, Clippy; there are also free alternatives (Jumpcut, ClipMenu), and the $2.99 but more sophisticated Clyppan along with its free, five-clippings-max sibling Clyppan Lite.