Since I've been so bad at not procrastinating, I've made myself a new set of rules for getting on with writing. So far, I've stuck to it and it's worked.
I'm not allowed any recreational internet, and I'm including social networking and blogging in that, until I've written at least 1000 words in the day. I'm allowed to play freecell while I wait for things to load up, but no other games, and no internet use besides work, novel research and checking my email.
When I get to 1000, I'm allowed internet, but I've renamed my Minecraft shortcut as '5000 words or no Minecraft'. If I ever get to 5000 words in a day and still have some day left to mine or craft I'll let you know.
There are two things that I think are making this successful. One is that it's concrete: I have a set minimum, rather than something like 'write more' or 'do as much as I can'. The other is that I won't be forced to compromise on it, because I'm only restricting non-essential things. I'd strongly recommend to anyone who's struggling to get something done to make themselves a productivity rule - make sure it's attainable, though - and do their d*mnedest to follow it, because productivity rules!
UPDATE: those of you who tweet, I've made a new hashtag: #dailyk