One common thing I do is start a set of applications and leave them open most of the day. Since I use the "Show Running Applications" (at left) feature of ObjectDock, this means I have several icons to the left. One thing ObjectDock lets me do that the Taskbar cannot is ordering those icons - for example:
AIM
Chat window
Chat window
Explorer with Music folder open
Winamp
Visual Studio Project A
Firefox with tabs open researching Project A
Visual Studio Project B
Firefox with tabs open researching Project B
However, the separators I've placed between groups of items in the list above aren't possible in ObjectDock - only the ordering part is.
It would be nice to group Running Application icons into user-arranged Groups. I could for example right-click Winamp's running icon and click "Create App Group" and I'm prompted to name the Group. I enter for example "Music" and I now have an App Group with Winamp in it. I can then drag the Music folder running app icon onto (into) the Music group and my group is complete.
To make these groups simpler to form it would help if Processes spawned from parent Processes were automatically grouped: For example, when I double-click a song in Explorer, it's that specific instance of explorer.exe that's going to start Winamp - that could implicitly create an App Group with those 2 apps in it. The default group name could be the title of the parent window.
The expanding group UI could be done in many ways - mousing over it might cause its icons to expand above it (in the Bottom dock case), or you might have to click on it to temporarily replace it with its icons - mousing away from them or clicking on one would collapse it back down. You could offer several optional group schemes.
A user who usually runs only a few apps at a time, or only a few this session, could ignore App Groups entirely, while someone who tends to take full advantage of multitasking like myself - I often have as many as 30 Apps to the left - could keep those well-organized and avoid them running off the screen.