Can you save groups of tabs in Eclipse so you can open them later?

Solution 1:

Mylyn should be your answer here.

Mylyn is a task-focused interface for Eclipse that makes working with very large workspaces as easy as working with small ones.
Mylyn extends Eclipse with mechanisms for keeping track of the tasks that you work on.

Mylyn monitors your work activity on those tasks to identify information relevant to the task-at-hand. Mylyn monitors Eclipse and captures your interaction in a task context.
System artifacts such as files, types, methods, and fields get assigned a degree-of-interest based on how recently and frequently you interact with them.
This results in uninteresting elements being filtered from view within Eclipse, allowing you to focus in on what is important.

Following Saheed's answer, don't miss CodeKiller's comment:

You can

• Activate the task to reopen all files and
• Deactivate the task to close all the files.

Bookmarks (mentioned here by user1039663) is a valable alternative.

Solution 2:

Eclipse provides multiple ways of structuring the IDE desktop:

• Perspectives: Customization of the positions of open and closed views and editors. You can copy and rename existing perspectives like the Java perspective and suit them to your needs by customizing them. See the Window menu or right-click on the perspective icon in the upper right corner
• Task Management Tools like Mylyn: see answer by VonC
• Multiple Windows: You can open new windows and move them to your second monitor. Select Window > New Window to open a new window. Each window keeps track of its own open editors.
• Multiple Instances of Eclipse: You can always use multiple workspaces and multiple instances of Eclipse. However, this is only recommended when working on different projects, as both instances would overwrite each others files when rebuilding.
• Hotkeys: By using shortcuts like Ctrl-T and Alt-Left/Alt-Right and Ctrl-Q you can quickly jump to previous locations where you have edited source files. This is a great help in navigating the open workspace.

Solution 3:

Extended VS Presentation provides capabilities to save sessions.

Unluckily, it only works with Eclipse 3.1 to 3.8:

Project page at Eclipse Marketplace