A feature that would be really good would be support for T1 or higher cards and bandwidth management based on user names. I would be greatly interested in the prospect of support for commercial or high end connections that support high rates of connectivity. Cards such as Sangoma, NMS CG 6060 or 6565, or BrookTrout technologies would give your users a much broader range of options and possibilities for markets or networks that are currently not supported with zeroshell.
just an idea.
chris