i haven't tested this, but you can probably use the 'Unreal Static Mesh' Exporter
http://www.neewo.de/OldSite/index.html
direct link
http://www.neewo.de/Files/USM%201.1%20Script.zip
with Blender
Blender
http://www.blender.org/cms/Home.2.0.html
(may need to use a slightly older version) to export some content (Unreal format is highly related to ASE). I don't think the above exporter handles animation though. May need a bit of hacking to get it working right.
Blender is Free under the GPL license (not certain what the scripts license is, have emailed the author).
If someone has a bit of programming skill, enhancing/creating exporters for Blender is really quite easy.
Here are docs on ASE format
http://www.solosnake.com/main/ase.htm
Also I read that the Milkshape 3d software exports to ASE.
Tom M.