I've released a new application, BlackBerry Alerts, for sale that may be of some interest. It provides capability for repeating audible alerts for:
Voicemail (may not always work perfectly since there is no access to the voicemail flag)
The alert can be set to repeat every 1, 3 or 9 minutes. There are a lot of options so it is highly customizable... mostly you will want to check out missed calls, sms and voice mail alerts.
You can set it up to use a profile so can choose any of your existing ring tones.
Version is compatible with the Pearl but there is an issue with the Pearl dialog for Missed Call view/close (thanks to PaulQ from this board for lots of testing). Still working on a Pearly Only version with Paul but license keys will be transferrable between the two. Product Link OTA Link (Demo Only, not available late night)
Let me know any problems/suggestions. Working on future version to include separate notification for each alert type. Free future upgrades provided (keep license key).