Redmine Jabberbot looks at the time entires tables and nags users for not entering their time
Per user customizable thresholds as well. The bot is configured to nag in a XMPP chatroom so everyone can see, but can report debug messages to one user.
(14:06:00) credilbot: metalman, bubbleman, flashman have not logged time in the last 4 hours
monthlyObjectives messages a user privately (via XMPP) to give the number of hours needed to bill today to reach a monthly objectives. See https://github.com/credil/redmine_jabberbot/blob/master/doc/monthlyOjbectives.md
Chitra is keeps tabs on hour banks. It calculates the number of hours billed since a specified begin date and calculates if the redmine user is ahead or behind. Results are sent by email, not XMPP.