Usually a fervent supporter of technology over anything, but I think I'd rather have that "huge calendar on the wall with a big red marker" than an iPhone (or web) app.
It's big. You wake up every day looking at it. And it brings us back in a connecting way to the real life.
Semi-unrelated: Same reason I'd still rather use a Moleskin to gather and write out my thoughts and ideas over TextMate, Photoshop, etc.
Streaks has been pretty effective for me; I used it to get myself to meditate every day. There's a little detail that makes all the difference: The app shows a badge on its icon that tells you the length of your streak. Skipped a day? No badge for you.
I put it on the home screen, so I get to see that badge many times a day, much more often than I would see a physical calendar.
Thanks for the taskmash link - looks neat. But my gut reaction is that seeing something physical, stuck on a wall by my desk, is more likely to be effective (at least in my case) as it's IMPOSSIBLE to ignore. An app/webapp solution is nice, yes, but there's no replacement for a huge oblong of paper with ink on it.
Let's see how I do. Will be printing or ordering a calendar this weekend
and a new site
tasksmash.com