Glipper is a good clipboard manager for Gnome. It has some of the advantages of KDE's popular Klipper but runs natively on Gnome desktop. Glipper keeps your selections history for you and lets you choose from a list of recent selections.
By default there is no clipboard manager in Ubuntu. It just uses xclipboard instead which unfortunately loses your selection when you close the application it was in and does not provide a convenient list of your recent selections to choose from. Glipper solves those problems nicely.
Install the glipper package from the Universe repository.
Glipper is now an application indicator - the icon in the panel is a clipboard with a G on it. Click the icon to see clipboard history and other options.