I once made a goal to brew a beer from each of the major style categories, so I printed out a chart and have filled in the blanks where applicable with each beer I brew. In the 2008 BJCP Style guidelines there are 28 categories, each with multiple subcategories. Realizing it will take awhile to brew each subcategory, I decided to focus on the main categories only...and even this seemed daunting at the time. Some categories I really don't have much interest in, such as Light Lager. Actually, if I limited the scope to just the ale categeries, I'm well on the way to completion.
Why do this? It's a great opportunity to learn about the styles. When you build a recipe for each style, you can literally touch and feel what goes into the style. As they say, learn by doing. As I set out to brew a particular style I will first read up on the style and then look at the ingredients and processes used for that style. Recipes for beers in that style will be compared. Grains, IBUs, water, yeast, fermentation temp, etc. all play a role...so there is a lot of opportunity to learn and experiment.
Note that I don't do this at the exclusion of brewing what I like or experimenting with different ideas. It is simply a good way to expand my knowledge and experience.
Let's break out the styles a little.
The first 5 are Lagers. So far, I've brewed 2 lagers. These take time and temperature control. I have only a small amount of interest in making lagers, so 2 for me is a very good start. The next 18 categories (6-23) can be classified more or less as ales, and the remaining 5 (24-28) as mead and ciders.
Where am I on with the ale list? 14 of the 18...wow. The un-brewed categories are (8) Scottish and Irish Ales, (11) English Brown Ale (technically my first ever kit was a brown ale, but I'm not counting it), (15) German Wheat and Rye and (17) Sour Ale.
So what is next? A Scottish style ale.