I have a web server running on a raspberry pi and I want to accept bitcoins. I have very little disk space so I don't have room to install bitcoind. I don't trust any third party services to process my payments so that wont work. Is it possible to accept bitcoins with my setup?
Any special situation for you to want your wallet IN your rapberry? A wallet doesn't need to be in a physical machine, actually it can be in a sheet of paper (cold wallet). So if you don't need your server to do anything special with those coins you can just create a paper wallet, and if what you really want is to check if you receive coins, you only have to check from your raspberry your wallet's public key in blockchain to see how many coins has it received.
If you want to create a wallet, you can use
vanitygen. Keep the public and private keys in a safe place and you are ready to go. The day you need to move those coins you will need to install bitcoin-qt wherever you want and import your private key to the default wallet created by bitcoin-qt. Once you've done that you can operate with your coins from that place.
You would need an SPV wallet in order to receive bitcoins. The only one I know of that's SPV and runs on Raspberry Pi is this Pi-Wallet, which uses electrum servers to detect payments: http://www.pi-wallet.com/pages/free-stuff
Note that it uses the Armory offline wallet built for Raspberry Pi to actually generate addresses.