Originally Posted by SagamoreAle
If I can buy it, usually I don't make it.
One of my baseline beers is an ESB that I've fine-tuned to something I really really like.
I do a lot of historical ales. One of my favorite references is "Old British Beers And How To Make Them" by the Durden Park Beer Circle. (self published, google if you're interested).
I also use "American Handy Book of the Brewing, Malting and Auxiliary Trades" published in 1901 by Robert Wahl and Max Heinus. A collection of pre-prohibition brewing techniques and beer styles. Available on Google Books. Includes a direct description of the elusive Kentucky Common.
There are plenty of other good historical brewing references on Google Books of you're interested.
I use source material as much as possible, rather than following directions from a web side that copied something from some other website that came from a homebrew forum that was copied from rec.craft.brewing (etc...get my drift?).
Where were you in my what to brew for 1920's themed party thread? :-p
But to answer the OP's question. I tend to brew mostly new recipes I've made myself from the bases of rock solid recipes I've found on the internet and made previously. Sometimes I try to emulate a beer I love, or to focus in on a flavor I'm craving. This winter was focused on heavy, imperial beers, this summer is looking to be a focus on lighter session ales and lagers.
I always try to add a new technique to each session or to just work with a ingredient I've never used before. I think it helps me grow.