When using skritter i usually have a yellowbridge.com tab open as well to check the etymology of some difficult characters to remember more easily. I noticed however that time doesn't stop when leaving the page (i mean checking another window or tab) and i don't even know if that is possible. It is not very important, but if you want to have those cute statistics and everything, and yes i too like these numeral gadgets, it will make their results less accurate. I mean regarding time per review, hours per day, etc.
A logical solution would be for me to remember the characters and check them later, but that is not easy while you are doing some heavy memory study at the same time. To cope with this a history of recently reviewed characters would be nice, maybe even with statistics per character (number of reviews, rights, wrongs, ...).
But hey, i know your to do list is already so huge haha, i am just spitting out my thoughts here.
I can't believe how much time I spend here, and to think i actually have a school holiday and just finished my exams. Yesterday i had to pull myself away from my computer or I would have started again at 3 in the morning, after finishing my work in the bar.