When it comes to nifty editors for Mac OS X there was one that I really liked named Smultron, by the swede Peter Borg. I felt that the application had about what I needed for a small-size editor and this morning I noticed that development of the product had been halted.
The reason for this Peter said was due to the amount of time development grab. The project can be reached on sourceforge.net though so hopefully someone else will pick it up so that it can keep on evolving.
Together with Smultron, Peter also noted that his two other projects Lingon and Hallon also was halted due to the same reason.