Gives theory behind the design of active filters. Covers not only the usual Butterworth, Bessel, and Chebychev implementations, but also the Sallen-Key, Twin-T, and Wien-Robinson. (Texas Instruments Application Report SLOA088.)
http://www-s.ti.com/sc/psheets/sloa088/sloa088.pdf
http://www.national.com/an/OA/OA-21.pdf
http://www.national.com/an/OA/OA-27.pdf
A Versatile Monolothic Active Filter Building Block
http://www.national.com/an/AN/AN-307.pdf
Discusses several applications of adaptive filters, and gives diagrams for the LMS and RLS algorithms, and for the transversal and lattice implementations. Also gives assembly language code for each of these.
http://www.engin.brown.edu/courses/en164/files/lab3_files/sharc_application_manual/chap6.pdf
Also gives a primer on probability theory.
http://www.cs.unc.edu/~tracker/media/pdf/SIGGRAPH2001_CoursePack_08.pdf
Lots of diagrams, apparently for a presentation. The text could use some elaboration.
http://www.eecg.toronto.edu/~johns/nobots/courses/ece1392/equalization2.pdf