Server Base - Evennia: http://www.evennia.com/ RPG System base - Pathfinder:
The Pegasus project is an open-source (GPLv3) suite of tools that facilitate the creation, administration and enjoyment of a text based gaming environment. Below you'll find a list of things on the roadmap, but suffice it to say that with any mu* server base that's available, there's always a need for good, dependable, standardized tooling that allows administrators and players to customize their experience. As Pegasus develops, more of the ideology behind it will be explored - watch for updates!
The Code Contributor's Manifesto(Queue the scary music, Dave) will give you all the information you need on how you can contribute to Pegasus. Both code and non-code contributions are welcome!
You may also want to keep an eye on our Issues section as Taladan will be migrating the systems that are under development to the issues board for input, unless someone else gets around to it first.
Note that we do not currently have a dedicated website, so if you're looking to contribute input on a domain name (pegasusproject.com is already taken, sadly XD.) or hosting or web design or anything like that, get in touch with Taladan and we can get grooving on that.