Custom profil field type

I’m planning to write some extension that add a new custom field type in the member profil section.

One problem : I’ve looked at the cp.members.php file and it seems that there’s no hook for that. Shall I add my hook manually or maybe there’s some other way to do that ?

The aim of my extension is to create some custom field type linked to a weblog entry. In example, we could have some “Product” weblog, and custom field type would let the user choose his favorite product in his profile.

Does someone would be interested in this sort of extension ?

Regards,