(I'm adding this, as it's a question we've gotten in email a time or two)
If you have any data that you DON'T want saved, we want you to have the power to deal with that. You have two options of dealing with "bad" data:
1. Navigate to that app and view the time period (using the cal controls) that you want to to delete it from. So, for example, if you surfed a jobs site yesterday at work, you'd go to yesterday, search around on your full app/site list to find the offending site, view it. On the bottom of the app/site view page is a "bad data?" area where you can nuke it. Another example is that maybe you've been playing Half Life 2 way too much and you want it outa there . Go to any detail view of Half Life 2, click the current month and, voila, the delete function will allow you to nuke the data for the whole month.
2. If this is recurring data that you'd like to delete, why not just add it to your ignore list? This is great for apps like Parallels, 3rd party screensavers that RescueTime might mistakenly decide are apps, etc. Simply navigate to a detail page of the app in question and (in that same "bad data?" area towards the bottom) click the ignore option. Henceforth, the data will literally never make it to our database.