I'm kinda annoyed with beer categories. Most beers I find interesting straddle 2 or 3 categories, but you have to play within the lines if you want to compete.

Here's how Beer Advocate breaks it down:

Hybrid Styles
-------------------------
Fruit / Vegetable Beer
Herbed / Spiced Beer
Smoked Beer

Hybrid styles are in the process of being sorted and moved into proper categories.
http://beeradvocate.com/beer/style

2008 BJCP Style Guidelines

23. Specialty Beer

This category can also be used as an “incubator” for any minor world beer style (other than Belgians) for which there is currently no BJCP category. If sufficient interest exists, some of these minor styles might be promoted to full styles in the future. Some styles that fall into this grouping include:

• Honey Beers (not Braggots)
• Wiess (cloudy, young Kölsch)
• Sticke Altbier
• Münster Altbier
• Imperial Porter
• Classic American Cream Ale
• Czech Dark Lager
• English Pale Mild
• Scottish 90/-
• American Stock Ale
• English Strong Ale
• Non-alcoholic “Beer”
• Kellerbier
• Malt Liquor
• Australian Sparkling Ale
• Imperial/Double Red Ale
• Imperial/Double Brown Ale
• Rye IPA
• Dark American Wheat/Rye

Note that certain other specialty categories exist in the guidelines. Belgian Specialties or clones of specific Belgian beers should be entered in Category 16E. Christmas-type beers should be entered in Category 21B (unless they are Belgian Christmas-type beers; these should be entered in 16E). Beers with only one type of fruit, spice, herbs, vegetables, or smoke should be entered in Categories 20-22. Specialty meads or ciders should be entered in their respective categories (26C for meads, 28D for ciders).

World Cup has a better range of Hybrid Styles:

Hybrid/Mixed Beer Styles

1. American-Style Wheat Beer
2. American-Style Wheat Beer With Yeast
3. Fruit Beer
4. Fruit Wheat Beer
5. Field Beer or Pumpkin Beer
6. Herb and Spice Beer
7. Chocolate Beer
8. Coffee Beer
9. Specialty Beer

10. Rye Beer
11. Specialty Honey Beer
12. Session Beer
13. Other Strong Beer
14. Experimental Beer
15. Indigenous Beer
16. Gluten Free Beer
17. American-Belgo-Style Ale
18. American-Style Sour Ale

19. American-Style Brett Ale
20. Wood- and Barrel-Aged Beer
21. Wood- and Barrel-Aged Strong Beer
22. Wood- and Barrel-Aged Strong Stout
23. Wood- and Barrel-Aged Sour Beer
24. Aged Beer
25. Kellerbier/Zwickelbier
26. Smoke Beer