I got some new books recently... (with Amazon Points)...
One that I'm really LOVING is called the "Flavor Bible".
The first part of the book discusses types of flavors (sweet, savory, salty, bitter, etc) and has input from many chefs world wide...
The MAIN part of the book is more like an encyclopedia -- Look up an ingredient, and it tells you what goes with it well...
Very, very, interesting.
If you mix your own rubs/sauces, you will really enjoy it, and maybe get some new ideas.