Yes, I do think ring signatures are the right direction, but the issue isn't necessarily with having a valid and anonymous vote.
The issue really comes down to the catch 22 of:

1. I must be able to prove or show to myself that my vote was cast, was valid, and was counted correctly. Others should not be able to validate/discover this.
2. I cannot be able to prove or show to others (1).

(1) seems possible, but (2) is the tricky part. If I can (in secret) show Bob that I voted for him, he could compensate me, and its right back to corruption being possible.