I like the mambot. It adds a lot of versatility to display of content.

One minor annoyance with it is that it inserts BR tags between some of the content it inserts. I think it's not a good idea to automatically add spacing to the content - that should be the site dev's choice.

A solution I would prefer is either adding nothing or surrounding the insertions with DIV tags of a particular CSS class so that dev can style the content as desired.

Overall very impressive.

I would definitely consider this extension for site memberships / subscriptions, basic product sales, and donation processing (due to the recurring billing option). Documentation is outstanding. The custom form builder is powerful, and while it's complex, there's a great tutorial in the docs.

The myriad of options for payment handling make nBill very versatile, and there are hooks for including custom processing functions.

One drawback: the component doesn't remove its database tables when uninstalled.

The email form function isn't really production-ready. Needs some hacking...