I have a GAZILLION cook books but honestly I find they date really quickly. Have you thought about cooking magazines? Australian Gourmet Traveller, MasterChef, Vogue Entertaining + Travel, Donna Hay, ABC Delicious just to name a few. I find them great because they tend to have a few different chefs and a variety of cuisines so it doesn't get as boring and I can work my way through one and then buy another when I run out of ideas again, I don't buy them every month but just now and then to add something new.

Try adding something different to something you already make, replace one herb for another you really like. Replace the chicken with a firm fleshed fish and so on, I rarely follow a recipe 100%. Try a different cooking style, something you usually cook on the stove top try cooking lower and longer in the oven.

Also when you're at the supermarket look out for those little freebie recipes that are usually dotted around the place, some have been surprisingly pretty good