I was always annoyed by the ajaxless slow github directory listing, especially on java-deep repos, when I stumbled on this project I found it a god-sent so I hurried to HN to post it.
I'd highly recommend the Bookmarklet and the Userscript. Both are real time savers. There are other enhancements that I have not had a chance to implement, such as bookmarkable URL and better syntax highlighting, hopefully GHF will be even better when that's done.