Maybe this is a total newbie tip - but I think it's very usefull, and I found it by mistake, so maybe others aren't aware of this:
In the live folders, (found in: add to home/Folder/Live folder) there's a folder called "Starred". You can place this on your homescreen, and when clicked, it contains all your favorite apps.
To select an app as favorite, you can get Apps Organizer from Market. It's free - and it can also be used to launch, label and uninstall apps.
When you have added the Starred apps folder on your homescreen (a yellow star) go to Apps Organizer and mark your favorite apps. (click the star to the right)
Now you have easy access to your most used apps.
And ofcourse: add Apps Organizer as a favorite app. This way it will appear in the Starrred apps folder, making it easy to change your favorite apps.
Edit: I see now, that this should probably have been posted in the Lounge or Application section... - sorry