Yes, certainly. I ended up using TOTP with an authenticator on my phone. Try FreeOTP[1] or if you're not fussed about pure open source, Authy is worth a look.
On the systems you can link it into PAM using Google's OTP plugin[2], either locally or via SSH etc.
It's definitely not that ground breaking but it works, provides reasonable extra security and meets my requirements. It lacks some of the feature of Yubikey like storing GPG on there or HMAC etc, but I don't need those functions in reality.
