Done on my Droid incredible using sketchbook mobile. Comes in handy for making thumbnails, since I can just do a thumb real quick when I take my kid to the park.
I hit a slump after the initial March Madness of 3 strips a week, plus health problems and being let go from work (on amicable terms). So my friend Sheldon Calbero suggested we start a drawing group to "sharpen our skills". Deadlines are 11:59pm on Sundays, and we usually pick a theme for that week.