http://w1.859.telia.com/~u85920178/use/filt1.htm
EDN-Design Ideas
http://www.edn.com/archives/1996/032896/07di1.htm
http://www.k1ttt.net/technote/onestub.html
This filter is a 0.1 dB Tschebychev lowpass with a rejection of 90 dB or better at 430 MHz, and 0.2 dB insertion loss at 72 MHz. The 3 dB cutoff frequency is 120 MHz.
http://www.northcountryradio.com/Articles/rcfltr.htm
Filter out any HUM that may be picked up by a noisy power supply or long wire connection.
http://members.shaw.ca/roma/nine.html
Actually a brochure for a design program, but shows lots of circuit diagrams.
http://www.nuhertz.com/filter/active.html
Application notes on active, passive and switched capacitor filters.
http://www.national.com/an/AN/AN-779.pdf
http://www.edn.com/contents/images/102600di.pdf