I have just started using pd, and here are some simple objects coming out of my early work. :) http://www.notam02.no/~kjetism/pd/bin/
k_sfinfo: gives info about a soundfile, such as type, samplerate, bits, length, etc. Using libsndfile.
k_varchange: Only sends output if the input value changes or receives a bang.
k_scale: Takes four arguments, x1,x2,x3,x4. Input is x, output is y. Does the following calculation: y=x3+(x-x1)*(x4-x3)/(x2-x1). Use it nearly everywhere, I guess there is some sort of similar object allready?