What is the best medium for sending feature requests? Both for Ubuntu as a whole and individual (supported) apps?
For individual apps, the best way is not Brainstorm, but filing a bug requests or feature request in the individual applications.
Some upstream development portals might be having explicit feature for asking user ideas but most of them use their bug tracker for that.
Example, you want a new feature in
Or before filing bugs for wishlist, you might want to talk to the devs of the particular application. You can look at their mailing list or IRC channel.
For Ubuntu, as Octavian mentioned Brainstorm is supposed to be a good platform, but sadly most of the ideas are neglected.
Recently Canonical CTO Matt Zimmerman mentioned that
That would be Ubuntu Brainstorm.
There you can propose an idea so other members can vote it up (promote) or down (demote) and where they can comment on your idea. Basically where you can brainstorm with other users.
Yes you can but this not the site for it.
Take a look at the Ubuntu Brainstorm Site which was set-up for just this purpose. Users can suggest new features and others comment and vote on these. I believe Canonical consider the more popular requests but a change being popular is no guarantee it will be implemented.
Depending on the type of request reporting a bug on Launchpad may be appropriate too. If its a request for a minor change file a bug stating its a "wish list" and what you would like. Wish list bugs tend to be low priority though. It may be better to try and find the upstream developers for that package and contact them directly.
If the feature: is can we include this package in the repositories you file a bug for that too and tag the bug "needs packaging" see here