I don't think it's possible for to fully explain how big of a difference Beeminder has made in my life. I was much like some of the folks in this thread (as in, starting projects but not finishing them; struggling to get stuff done), but since implementing Beeminder in my life, my productivity has gone through the roof. It's also given me a lot of self confidence in my abilities, which is pushing me to take on more ambitious projects and ambitious tasks.
The focus on averages is definitely what I like most about Beeminder.
On more than one occasion, I've fallen asleep without writing my daily 750 words, only to wake up 20 minutes later in a cold sweat, rushing to my laptop so that I can quickly write my words so I can get back to bed.
With Beeminder, that's not a problem. I usually have reserves built up, or, alternatively, I can simply put in some extra time the next day.
Case in point, last Friday, I went to the doctors for a routine asthma checkup and they gave me a flu shot that completely knocked me out. It effectively ruined my plans for the day. Instead of worrying, I went home, rested, and put in some extra time on Saturday instead. It's simply not possible to do this with the Seinfeld method.
One thing I forgot to mention in my earlier post is that I heard about Beeminder through Nick Winter's book 'The Motivation Hacker'. http://www.amazon.com/The-Motivation-Hacker-Nick-Winter-eboo...
It's cheap, it's a quick read, and it's got some great information inside. I made some notes while I was reading the book - I've uploaded them here: https://www.dropbox.com/s/9f6xofet38ka1x2/Nick%20Winter%20-%...
If anyone's on the fence about buying it, it's definitely worth picking up, in my opinion. There's a lot of great stuff in there that I didn't cover in the notes.
Cheers again, man.