Take a look at www.phonefactor.com.
My company has started using it instead of SecureID.
It works and is/was free for less than 25 users.
We log in with login and password and the system sends an ssl messge to phonefactor’s servers for authentication. Their servers call our cell phone. When we answer and press the # key, their servers send a message back describing the transaction.
It works very well.
Dennis