Currently I'm founding a small internet company with several friends. We'd like to use web-based collaborative groupware (e.g. eGroupWare) to coordinate our activities. Could you recommend free software which implements a portal that approximates the following features:
-blog-like forum, where any user can post and new posts appear first
-follow-up comments can be placed within parent postings (rather than having to place all responses after the parent posting)
-attach binary files to postings
-automatic email notification of registered users when a new posting is made
-spreadsheet or some kind of log to keep track of expenses, that everyone can edit (I guess a wiki would do)
-todo lists for each member, that are both readable and writable by each registered user
Presumably such an application would be written in PHP and run on Linux.
Thanks in advance for any advice!