A 2.3GHz to 432MHz receiver converter by DL5NEG
It is a very small receiver converter that can be plugged to the backside of the battery powered portable transceiver FT817 from Yaesu. It runs on the batterys of the transceiver (no changes to the transceiver necessary).
http://www.herbert-dingfelder.de/ft817_conv_13cm/converter.html

A programmable 13cm to 2m RX converter by DL5NEG
There are a lot of 13cm RX converter concepts. Most of them use a multiplied crystal oscillator to generate the necessary LO signal at 2176 MHz. I have also seen a few that muliply the crystal frequency using a PLL ...
http://www.herbert-dingfelder.de/new_13cm_conv/converter.htm

A Subharmonic RX-Converter for 13cm by DL5NEG
The receiving converter consists of three modules. The preamplifier, the local oscillator (1088MHz) and the subharmonic mixer itself.
http://www.herbert-dingfelder.de/old_13cm_conv/13cm_con.htm

An S-Band to 70cm Receive Converter for Phase 3D by GØMRF
A recent survey of satellite users world-wide revealed that only 3 percent were active on mode S. With the re-entry of Oscar 13, we will have now sadly seen the end of a mode S transponder that has given years of reliable service ...
http://www.g0mrf.com/sat.htm

Gemini: A 2400 MHz to 28 MHz converter by GØMRF
This dual conversion receive converter is currently undergoing final testing. It is a joint project between Sam Jewell G4DDK and David Bowman GØMRF.
http://www.g0mrf.com/gemini.htm