Just released into the wild is Analog version 0.5, now with a proper home on the internet with downloads, a feature list and screenshots. It's a freeform map editor for 2d games that's based on vectors rather than being tile-based.
I started work on Analog over a year ago when I wanted a flexible map editor for Rescue Squad 2, I looked around at various free tile-based editors but they really didn't match what I was looking for. For Rescue Squad I wanted free placement of buildings, items and so on rather than being locked to a grid. Since then I've added support for rectangles, polys and poly lines, and also used it for NiGHTS4k.
It saves into xml format, and you can plug in your own export scripts (written in Java/Beanshell) so you can easily export to another format that's crafted specifically for your game. This came in very handy for NiGHTS4k as I could write the levels into a highly compressed binary format to keep the size as small as possible.
Anyway, have a look and maybe a play with it and let me know what you think. If you're wanting to use it for a game but it's missing an important feature you'd like then don't hesitate to drop me an email or a comment here and I'll see what I can do.