Some of my favorite laptop accessories:
Zeroshock laptop sleeve - These are composed of a high-resistance polyurethane foam and provide excellent protection against impact. I have purchased a total of 3 of these so far (iBook, MacBook, and ThinkPad). I don't buy a laptop without one of these now.
ShaggyMac screen saver / keyboard cover - These lay on the keyboard and cushion the screen when the laptop is closed; preventing damage, scuffs, and other screen marks created by the keyboard. They also double as a "professional grade" optical polishing cloth...perfect for cleaning your screen. Same as with the ZeroShock...these are mandatory for me.
iCurve stand by Griffin Technologies - Raises your laptop up to eye level, provides increased airflow underneath to keep it cool, and just looks cool. (unfortunately, these are no longer made...glad I bought mine when I did!)
