How do I show my wallet from the command line? How can I show/open my wallet in gui-less linux version? I tried to show the contents with cat but it's only binary data (which makes sense). The --help option of bitcoin/bin/64/bitcoind also doesn't give me a hint.
Direct command-line access via bitcoind is not available any more. You can get access from the command line via the RPC (Remote Procedure Call) API, e.g. with python. The API calls list is found here.

To give a specific example, you can access wallet information via the Python RPC API. Given that the client was booted with rpcuser=user and rpcpassword=pass, the sample python script illustrates how you can call the getbalance command:

  from jsonrpc import ServiceProxy

  access = ServiceProxy("http://user:pass:8332")
  access.getinfo()
  access.listreceivedbyaddress(6)
  print access.getbalance()