The Web Part Page Maintenance page is where you can go to see all the web parts included in a web page and perform some limited maintenance activities. To get there, simply append ?Contents=1 to the URL of the page (ex: http://somewhere.com/Pages/Default.aspx?Contents=1). The page which appears lists all the web parts which are included on the page. From there you can choose to remove (Delete) web parts or remove personalization (Reset) for specific web parts. Personalization can be removed for all users (the default) or you can switch to personal view and remove personalization for just the current user.

This SharePoint feature is really handy if one of your web parts is throwing an error preventing you placing the page in Edit Mode. In this case, you can use the Web Part Page Maintenance page to remove the offending web parts.

Thanks to coworkers Kirk Liemohn and Chris Edwards for this great tip!