there are also linear encoders, low-cost, a small plastic tape with small lines (like the rotary encoders but linear)
and some gearhead motors with encoder witch is VERY useful for robotics. i believe that this is something that really misses from sparkfun…
I like very much sparkfun it saves me a lot of time and money and encoders are something that i and many others need for our projects… I’d like to see some of this stuff…