I've just made a map of tags for Physics.SE.
In short: tag size is related to tag popularity and edges are related to tag co-occurrences in questions.
For me it looks as a "snapshot" of topics and scope of this SE site. So if you want to you it in any way to promote Physics.SE - feel free!
Also, if you have comments how to improve its usefulness or niceness to our community, I would appreciate them (but bear in mind that I have no color esthetics).
- An entry for StackExchange vis competition at Kaggle (please vote if you like it :), it ends on Nov 3)
- Recipe, code and images at GitHub (e.g. tweak the plot to your taste; feel invited to co-develop)