For the record, I'm a big fan of #2. I have been the guy answering the phones for NPR pledge drives and what I find is that people love to donate and feel like they're supporting something they value, not just for themselves but for others as well. I'm not sure what a Hubski pledge drive would entail or if it would even need to exist, but I'm sure we could figure out a way to make it relatively non-invasive, interesting and even fun.
Thirded. I'm not a fan of this whole bit/hubs transaction model, I would only ever provide a transaction to the content submitter if it was original and outstanding and all I'm interested in is being able to give you all money to keep this site going. Anything else, to me, is unnecessarily complex but I understand that my opinion is not in the majority and not at all representative of running a site with many, many users. Given that opinion, #2 is the option I support the most and it would make me feel better just being able to donate the money than getting bits/hubs/whatever. However, I also support veens idea of Hubski2Hubski gifting for donations. That's an interesting idea.
Seconded. I spent a couple of evenings answering pledge calls for CJSW and everyone was very happy to donate. Maybe something cool to throw into the mix: what about gifts from other Hubskiers? At the radiostation, the hosts gave away some of their own cd's and things that they thought were awesome. What if we tie a small gift exchange into this? E.g. if you donate more than $50, $10 of that will be used to fund shipping of a small gift from one Hubskier to the next. This way, people who don't / can't donate money could make artwork or donate a good book to another Hubskier.
I like it too. My favourite radio station, Intergalactic FM, has a "monthly struggle for survival" progress bar. It's nice to see a visual indicator of the community's efforts to keep the site funded and there might be some interesting things Hubski could do to make it engaging.
I'd be interested in something were every quarter (every month? every other month?) Hubski does a donation drive to reach some amount to keep the site stable. It would be cool if a certain portion of each donation went to a community-chosen charity as well. At the beginning of every cycle a funding goal is announced and people can nominate charities for Hubski to sponsor for that funding cycle. Kind of similar to how Humble Bundle tie purchasing video games to optionally supporting the site and supporting a charity.