I have written a simple wrapper around tex4ht to convert tex files to html. This is slow, and currently noisy. I do not recommend it for running from cgi. But for interactive conversion of my old tex4ht based home page, it seems to work OK.
The current version is available from git
Other related ideas/plugins:
pandoc can also convert latex to html or markdown. It is much faster than tex4ht; on the other hand, the rendering quality is not quite as good, and pandoc does not understand user defined TeX macros.