Support for MailChimp multiple lists

I need one form to subscribe to one MailChimp list and another form to subscribe to a different list.

I've had a need for this in the past and now a client requires it too. So I thought I'd add it as a suggestion.

I'm not sure what I'm going to do in the meantime. Ask the client to add subscribers in manually I guess. Does anyone have a work around to this?