StarterKit

Well, I would get a bigger breadboard like one of these:

http://www.cutedigi.com/product_info.php?cPath=243_280&products_id=4314&osCsid=3fdb024298dd8537fa68987f9316daba

http://www.cutedigi.com/product_info.php?cPath=243_280&products_id=4304&osCsid=3fdb024298dd8537fa68987f9316daba

But the small breadboard is good for little projects, and if you plan on buying a Protoshield, it fits right on top.

I would also look into getting some LEDs (although that kit comes with several) and maybe an LCD as well.