I just started twittering and have found that getting alerts on my phone is great, just not when I’m also at the computer.
So being a good geek I thought I’d automate the process of turning mobile alerts on or off based on my laptop status.
So far I’ve scraped the HTTP headers and post variables so I know how to login and turn updates on or off. Next I need to package up a small utility to automatically decide when to send the commands.
I saw Simon demo Primecondition.com at last months Refresh Phoenix meeting and I have to say that I was impressed.
The gist of it is you create your workouts. Input your exercises, sets, reps, times, etc and the app generates an audio track for you. The generated track has all the verbal cues that a personal trainer would have for you at a much lower cost 
You move the track onto your iPod or whatever device and hit the gym. It walks you through all the stuff that you have defined in your exercise while playing music to workout to.
This is a great application! The fact that its on the web just makes it easier to use and talk about and enables the sharing and community features that make apps so much more sticky.
Check it out if you need someone telling you what to do next at the gym.