IPad accessories I should buy

A good screen protector (like Power Support's crystal).

A Bluetooth keyboard definitely comes in handy.

depends on what you are going to do with it and where.

if you are just going to be on your couch surfing, then save your money.

but if you are going to travel with it and type frequently, get the dock/KB combo

think about uses first and then go from there.

I prefer the Bluetooth keyboard to the dock\keyboard combo because of the need to take the iPad out of the case with the dockable keyboard. If you use a slip case rather than a folio type case, you would fare better with the dock/keyboard combo though.
brn2ski is definitely right. To get the best answer it would be nice to know how you use it.

Targus stylus for taking notes or drawing on the iPad. Best Buy sells them for $14.95. Way better than the Pogo IMHO.

-Power Support Crystal Film (or Anti-glare, depending upon your taste)
-Yoobao Magic Case or Chinao
-Apple Wireless Keyboard
-Neoprene Sleeve

Other "nice-t0-haves"...

-Additional (cheap) silicone protector for when you use (possibly) your iPad without the case (these are very cheap on ebay. I just found an awesome clear one that doesn't cover the bezel).

-Stand like the Mac4u adjustable stand (also available on eBay from other sellers)

-Car Charger

-External battery (not a priority due to the iPad's extended battery life)