I wonder if it would work for companies/services to offer perks to their users in exchange for donation to Mozilla? It's a weak example but if, for a $50 donation, you could get an icon on your HN profile -- and that shows up with your comments -- that you're a financial supporter of Mozilla that might drive donations. Granted, HN is a pretty small community but if, say, Facebook offered a perk level for supporting Mozilla it might get the network effect going perhaps.