Ideas

[flowtron]

Your idea re:serverbrowser has already been discussed inside the dev-team,
especially with the advent of all the new flags AC-servers can have I find this is definitely needed. There are some issues to get nailed down though, before anything is done here. It needs to be clarified exactly what extra information is displayed and how, I'd prefer a set of icons or radio-button-like toggles for the most common stuff - like "allows coop", .. but there you go - there's a lot of different aspects to coop itself (upload map allowed for player or admin?) .. it means there'd have to be a good iconography or more states to each toggle than just on/off. Anybody willing to doodle up a sketch of how they'd imagine the serverbrowser to look with all data viewable - your input would be more than welcome.

Custom/Variable gamemode - this is not something I could imagine to be readily implementable - your own argument (at least) makes the result a questionable matter; some points on your list are simply not possible from the cubeengine. But some aspects could be made to work for all modes, like the toggling of pickups and/or spawn-state.
It'd make match-voting a lot more complex, but maybe that's a good thing ;-)