25¢ Growth Special
blog.gittip.com
blog.gittip.com
I don't instinctively think that the $1 minimum was a problem. When Gittip was first mentioned, I asked to be able to give tips without signing in first with Twitter or Github; I have accounts with neither service. For example, you say, "...the number of givers on Gittip is really, really small (279) compared to the number of people who, e.g., are on the Internet (2,450,000,000 [source])...", but you aren't making your service available to everyone on the Internet.
Maybe with the recent fraud problem you'll be forced to stick with requiring Github accounts for tippers (though I don't see how a Twitter account would meaningfully alter the metrics for fraud), but I really wish there were some way for me to just hook my business credit card into your service, point it at some guy on Gittip, and send him money each week, without having to create an account on another service first that I don't need.