TwitApps provides services to augment the usability of the Twitter service. Currently this is limited to email notification services, specifically of mentions and follower changes, but additional features are planned.
The Replies service (named before Twitter renamed replies to mentions) is designed to send email notification when other users mention your username. Among other options you can specify how often these emails are sent and whether it is limited to replies only rather than all mentions.
The other service is Follows which performs a similar function to Replies but for your followers. You can configure it to check your follower list daily, weekly or monthly and it will send you an email telling you who started and who stopped following you since your last email. This service is designed to replace the individual emails you can get from Twitter for each user who starts following you with a single email that also includes users who’ve stopped following you. For users with a large follower list this can be an invaluable time saver.
There is also an option to have your follower changes POSTed to a URL in JSON or XML format rather than using email.
