I'd be fine for donations - however, there's another venue I could see we could use (of course it has flaws, what system doesn't).

Buying "premium badges". Either allow people to gift a normal badge (as in, instead of the post being marked as badged, the user itself gets a new badge to put to a post) to people they particularly resonate with (in a show like "I can't buy you a drink so have this badge instead"). Or have another premium (platinum?) badge that shows beside normal badges. But the point stays: you could offer to us to buy other people badges. There's plenty of disadvantages (mostly it monetizes part of an important aspect of Hubski, admittedly, and it may help people fortify their echo chambers by idolizing members but anyway), but personally I see two advantages: it may help people who generally give thought-provoking posts, or read and share powerful conversation starters, to get more visibility and stimulate interaction and discussion, all while not hiding any feature from the free user (at best, the result is pretty much invisible to the user, at worst people can see it but still have access to every single thing - and except in close-minded communities, a platinum badge will not be seen as a symbol of status since you should be unable to buy them for yourself and gain absolutely nothing from having them).

Just my two cents. Similar to Reddit Gold but with less importance to the user.