Languages like C# 3 have come on great leaps and bounds when it comes to allowing a functional programming constructs. However, they are at heart imperative languages. I wonder whether you could use FxCop/Code Analysis rules to try to bully yourself into correct behaviours, like using immutable variables.
I have no idea how to go about doing this — particularly, I don’t really understand what the rules should be — but I think it would be interesting to develop a C# project with a set of rules promoting a functional style; it might be easier than, say, learning F#.
