+1
You could use the password for "settings", which is currently unused. If I "log on" with password "share0.01" then I'm stating 1% of my payout should be donated to the pool. "share1.00" would be stupid, thus ignored / set to the highest possible donation (10%?).
I would really like to donate to you on a regular basis and more so automatically. Like scraping off the "change" from the full bitcoin. (I never get more than 1.2 on any payday because of my low hashrate)