When a community is deleted, the community's views would be replaced by a page that notifies the user that the community was going to be deleted, and if they objected to the deletion to click a box and press a button. If x% of the members of the community objected, it would immediately be reactivated. If, after y days the necessary number of objections haven't accumulated, the community is marked for deletion.
Of course, this raises a few problems. First and foremost, if the maintainer of a community really wants it deleted, that person can just delete the community over and over until the members finally get so annoyed they don't vote to keep it. I think the best solution to this would be do not allow another deletion attempt for a (fairly ample) amount of time.
Also, what happens with communities that have only one or two members who keep objecting just to piss off the maintainer? There should be a lower limit (probably when x% of the users is at least 3 or 5) on when this becomes necessary. If the minimum number of members is not met the community can be deleted freely.
My main issue with deleting communities is that the Internet and permanence are not the best bedmates, and the namespace for communities and users are not separate.
I think this post is better suited for this community than for suggestions since this is intended more as a followup to previous discussion in lj_dev, but if you all think otherwise, I'll delete it and repost it over there.