Springtomize 2 is a very useful tweak for customizing your springboard as the name implies. Icon resizing, label removal and the coverflow effect on the dock are my favorite customizations. There are also many nice Winterboard and Dreamboard themes available for a jailbroken iPad, the best ones cost a couple bucks and are well worth it.
There are many more things you can do with a jailbroken iPad, you won't realize what you have been missing until you download a few tweaks from Cydia and wonder how you live without them! Check out the best jailbreak tweaks for the iPad, drop a comment with your favorite(s)!