Compatible with modal_forms

Great idea,

I will get on that!

I checked the Modal Forms module and it actually is quite limited right now in terms of which forms it supports.
However, it gave me the idea of other things that can be achieved by allowing to add classes to the links.

So in the latest dev version you can now add CSS class names to the links as well as query strings.
That will enable users for example in connection with the Colorbox module to create overlay links. Another use case would be to pass arguments along to a webform.

Hope this new functionality will help you.