The Hubs idea looks like it is a good one. I have a boatload of tools
that I am sure would be useful to other IETF-ers but when I am at a
meeting I am busy working on protocol proposals the tools were written
to support. Meeting up on a local basis is probably a better idea.
In addition to geographic affinity groups, there might be a utility to
other community groups. In particular academics.
Every year, people who are teaching courses are looking for
interesting project proposals for their students. This is often the
thing I am asked about at MIT.
The project I am working on right now is designed to allow us to start
making use of some of the more interesting public key cryptography
beyond simple encryption and signature. It also provides a way to
start experimenting with new trust models. There is a lot of scope for
student projects at every level.