On the Web, there’s a never ending supply of sites and services that ask permission to use your accounts at Facebook, Twitter, Google and other services. Over time, you might grant access to hundreds of ’em — including ones you forgot you ever used in the first place. Enter MyPermissions. It provides convenient links to the permissions pages at major services, letting you do quick reviews on the rights you’ve granted and, if appropriate, revoke some of them. Apps for iOS and Android provide further permission-cleansing tools.