I used a shop that uses the Shimano fitting system:
Home | bikefitting.com
They were able to figure out my correct bike geometry and then translate adjustments, using lasers, onto my existing bike. It turned out my bike was a bit too large (56cm, really needed a 54cm) so I got a printout of what would be "ideal" for me, and then went looking for a bike/frameset that most closely matched those measurements. I must have poured over dozens of frame geometry charts before deciding on my current frame. Once I got all my components (frame, seatpost, saddle, stem, bars, wheels and groupset) all together and assembled, I brought it back down to the shop. Thier computer stored all my info, so it was just a matter of setting up the lasers again and making the adjustments on my new bike.
Well worth the money to me.