You can browse the status of the class library and see who has registered to work on what parts of the system. You can view either by maintainer or by namespace.
The tables represent things that contributors are working on. We register the date when they started working on a particular class, and whether a contributor has sent code in (the "implementation" column).
If you want to contribute to Mono, you want to pick a class which is not listed here. Alternatively, you can contact the maintainer of a class if you want for example to help him improve his code, make it faster, better, provide documentation or make comments.
Sometimes contributors will get too busy with other tasks, so they will abandon their work on a class. That is why we keep track of the time when they "reserve" a class to work on. If the contributor gets too busy, we will know if someone else can work on it