Steve,
just been wondering if you had a look at the registry (http://oscommerce.sammysolutions.com/registry/index.php).
I need to built a system for standing orders and I think the registry/wish list could be used for this as well (all products in the registry could be billed recursivly.). Not 100% sure if I can get it going that different products have different billing cycles. But this shouldn't be too hard to do.
If you are interested and you think this can work, we might could join forces in that.
Let me know what you think.
G.