The stuff here is a bit old, but I think some of it is still interesting.Random Agar v1.1 (released October 2002). This program is intended to look for new Life oscillators, wicks, and agars. It generates random spatially periodic patterns, and runs them until they oscillate. It includes complete support for all possible symmetry types. See the program's Read Me file.
The photon/XOR system (October 2007)
The 17c/45 Caterpillar spaceship (Updated January 2005)
Lightspeed signals in Life (Updated December 2008)
Still lifes or pseudo-still lifes?
Catalyst v1.0 (released 2001). This program finds ways of modifying the evolution of an input pattern by placing catalysts that react with it, by a backtracking search.
Stable and Glider (released February 2000). What if a glider collided with a group of simple still lifes, generating a glider in the opposite direction, and then the still lives re-appeared in their original configuration? While a little bit unlikely, such a reaction (or a couple of them) might lead to an arbitrarily-slow spaceship or a new stable glider reflector. With this program I tried systematically to find such a reaction, and I didn't find anything (although I didn't exhaust all the possibilities).
Zig zag (June 1998). Gliders from a rake are bounced back and forth forever by heavyweight flotillas that come out of an assembly of guns.
"Frozen Decay". Abstract art.