I don't think there are any. If there were, there's a good chance that it wouldnt' be very legal to distribute them over a forum.
I think learning to program a PIC in C really involves learning each of them separately to some degree...
1) learn to program in C on a computer
2) learn about PICs, getting at least moderately familiar with the architecture and everything, preferably by trying out assembly programming.
3) finally put the two together, by using example code and documentation for your C compiler, so that you can identify the ways in which things are done different for a PIC in C than they are in standard ANSI C that you'd use on a computer.
I think if you try to learn both of them at once from scratch, rather than learning some about each of them separately and putting it together, it will be more difficult.