efileman is simply the best, most versatile tool I've ever seen! Although it was originally written to be a file manager, I've successfully created a free website hosting company from it! It's got everything I could need for either purpose, built in WYSIWYG, user registration, forgot password, template-based, etc.
It also has the best documentation (on its website) and the greatest support forum, the owner replies to almost everything within a day. Plus it's free and works on almost every sever!