Do you buy pdfs? If so there are a lot of cool monster books that are in just that format:
Complete Minions (Bastion Press)- interesting, different, but not too different creatures
Book of Templates (Deluxe Edition) (Silverthorne)- 3.0, but for 12 bucks, you get 260 pages of templates. The non-euclidian and half-humanoid (actually 4 templates in 1) plus the suggestions on stacking templates are worth the price alone IMO.
(Side note on Advanced Bestiary from Green Ronin vs BOT(DE)- AB has a better explaination on how to apply templates and BOT has better rules on using and stacking templates. I like the latter more, but both are supremely useful in customizing creatures).
Template Troves I & II (Silverthorne)- specialized pdfs of templates. The first one has a bit too much Norse mythology in it for me, but does not just have Norse based templates. The second one, on oozes and aberrations, goes nicely with Lords of Madness.
Brixbrix's Fieldguide to the Creatures of Ados (Tangent Games)- This one is organized by creature type, then alphabetically. Some of the high points are new rules for undead plants, 2 dragons, 10 drakes, new animals, more than one page is devoted to each creature, and each has hooks and a short adventure. I bought it on a lark and am very happy with it.
The Iconic Bestiary: Classics of Fantasy (Lion's Den / Ronin Arts)- Creatures that fill the same niches as closed content monsters in the MM. Even if you don't want a new version of illithid, umber hulk, carrion crawler, beholder and displacer beast, the slaad replacement is more chaotic than frogs and the yuan-ti replacement has an interesting caste twist (the former servants now rule).