I know this is only a stub - I'll add more once I have some time.

A Module System for Twelf

Together with Carsten Schürmann, I have designed and implemented a module system for  Twelf. Implementation and documentation can be found as the  mod branch of Twelf.

It is used extensively in the  LATIN project.

jEdit Mode

More information on my jEdit mode for Twelf can be found  here.