doing a quick google search i found this book:
Interfacing PIC Microcontrollers: Embedded Design by Interactive Simulation
it says it has many examples of assembly source code for PIC16F877
This looks to be a good book, Admin - From your comment though, it sounds like this is just one that came up in a search? If so - have you heard positive comments on the content; or, can anyone on the board that has a copy reccommend the book for PIC users (I'm using both 16F and 18F PICs)?
Another book - one that I use and highly reccommend - is "PIC Microcontroller: An Introduction to Software & Hardware Interfacing" by Han-Way Huang.