Lots of good ideas here!
I like Gavin’s idea to display full precision in the UI and allow it on payments.
I like ribuck’s terminology: 100 bitcents in a bitcoin, 1000 millicents in a bitcent, 1000 microcents in a Millicent.
I like [mike]‘s suggestion to allow miners to store information relating to costs and policies, and to adapt network behavior from that information. I’d suggest using it specifically to normalize the “anti-spam” limits: the 0.01 minimums for large-transaction fees and for free transactions. Clearly Bitcoin needs a way to adjust these values, and Mike’s proposal seems like a good candidate.
I also wonder if the anti-spam rule shouldn’t be changed, to trigger if the largest output is tiny, rather than for any output. In Gavin’s example, outputs of 1.5 and 0.000001 change seem ok to me.
