I built a little tool, which I thought HNers would find fun. You can play with it here:
http://checkintext.appspot.com/
Follow the instructions at the top, and you'll appear on the page.
If you're on a smaller screen, you might benefit from zooming out.<p>The story behind it is over here: http://www.ousbey.com/blog/check-in-app<p>Do let me know what you think!
Clickable links:<p><a href="http://checkintext.appspot.com/" rel="nofollow">http://checkintext.appspot.com/</a> for the app<p><a href="http://www.ousbey.com/blog/check-in-app" rel="nofollow">http://www.ousbey.com/blog/check-in-app</a> for the blog post about it