I was thinking about getting a new bike a few months ago - maybe even a custom bike, and so I started looking at the questionnaires the custom bike places ask you to fill out to help determine geometry, components, material, etc. I quickly realized that I had a LOT more to learn about cycling in general and my own preferences, strengths and weaknesses. I have been trying to "study" my rides with these questionnaires in mind, and I find it really has helped me think about what I ultimately might want - even though I'm not ready to make a descison yet!
here are some links that might be interesting:
Seven Cycles - custom fit kit (oooh - I love Sevens!)
Luna Cycles - custom questionnaire can be downloaded
Keep calm and carry on...