Keeping link lists up to date is difficult. For a more extensive listing or if one of my links is dead try Ralph Wallio's ARHAB link list.
I keep a copy of this page HERE, but it isn't going to be as fresh as Ralph's.
HomepageRadio Club Satelite Home pageThe latest balloon information
Gustavo Carpignano's Balloon and Amateur Page
High Altitude Glider Project
Cygnus High Altitude Balloon - Poland
ILMARI-2003 - Finland