You might imagine that a utility as simple as a multiple clipboard would have become standard on the GNU/Linux desktop. All it needs is the ability to copy and paste text and some popular graphics formats, plus some basic controls to set the number of stored items and to clear the memory. Yet, although at least six multiple clipboards are available, choosing which to use is a matter of trade-offs that depends partly on your desktop environment and partly on which features you want.
For some time, a multiple clipboard was one of the inexplicably missing utilities in GNOME. However, in the past year, Glipper has corrected that oversight. Originally written C, it was recently rewritten in Python, and is now the fastest-acting of all the clipboards I have seen. One especially promising feature is its ability to use plugins to extend its functionality, including the setting of actions to perform when a regular expression is matched in a history item, such as opening a Web browser when an URL is copied.
However, Glipper works only with text, and, according to the About page on the project site, Gipper's developers "currently have no plans to manage any other type of data." In addition, it does not work outside of GNOME, and the latest version can be buggy, at least in Debian and Fedora, where it often fails to load as a panel applet the way that it is intended.
Parcellite, another clipboard for GNOME, is heading in the opposite direction from Glipper -- it's about to switch from Python to C in its next version, but has much the same functionality.
On KDE, Klipper has been around for long enough that it is the template for most of the other clipboards, having standardized such elements as the use of Ctrl-Alt-c for opening a popup history beside the cursor, as well as other standard options. It is capable of working with graphics, and, uniquely among these clipboards, it comes with a complete online help system.
Klipper's only drawbacks are that it can be slow with some applications, including the GIMP and OpenOffice.org, and, at least in my experience, is as apt to record the name of a graphic as display a thumbnail. Still, Klipper remains one of only two clipboards that has the full range of functionality that you might expect. Even if you use GNOME, you might still want to enable Klipper on your desktop.
Another promising clipboard is part of Desktop Data Manager (DDM), a multi-functional project that also includes a download manager and a screen capture application. Unlike Klipper, DDM reliably loads thumbnails into its history, but unfortunately, little work seems to have been done on DDM in the last eleven months since Linux.com reviewed it. Outside of Ubuntu, it remains difficult to install, even on Debian.
Some users may also be reluctant to install DDM because its dependencies include Mono. Even if you do not object to Mono as an implementation of Microsoft's .Net or as possibly patent-encumbered, you may well decide that it is too large an infrastructure to install for a small utility.
If you run Window Maker, you might try wmcliphist. This utility features a configurable number of items to keep, the option to save the clipboard history when you exit your session, the ability to open a pop-up window beside the cursor, and to automate actions with keyboard shortcuts. A unique feature is the ability to lock selected or all items in the history, so that they are not overwritten automatically when the history is full. Its drawbacks are an inability to copy and save graphics, a limited set of options compared to other clipboards and the inability to run outside Window Maker, which excludes those who want a simple clipboard but prefer another graphical environment from using it.
On the Xfce desktop, the multiple clipboard is called Clipman. It is more graphically oriented than wmcliphist. It also has a few more options, including the ability to prevent an empty clipboard, and to maintain Clipman independently of the standard Xfce clipboard -- although there seems little reason to do so. In addition, although its standard behavior is to copy any selected text, you can also set it to only write items to the history when you deliberately copy an item. Like most of Xfce, Clipman strikes a reasonable balance between customization and responsiveness for most people, but, like wmcliphist, it is usable only in the graphical environment for which it was designed.
Making a decision
None of these clipboards wins an unqualified recommendation. Of the five, Klipper comes closest, assuming that you can use it in the graphical environment of your choice and have the patience to endure its occasional quirkiness. If you only need a multiple clipboard for text, you might be better off with wmcliphist, Clipman, Glipper, or Parcellite. Until someone writes a reliable, full-featured clipboard, your choice will be a matter of deciding where you can compromise and what shortcomings you can live with.