Came across Andrew's post about how to create a custom timer job in MOSS. I'm working on a Lotus Notes application migration project and I'm planning to recreate some Lotus Notes application Agents (scheduled jobs and notifications) in MOSS using custom timer job. Will post follow-ups on this later...

http://www.andrewconnell.com/blog/articles/CreatingCustomSharePointTimerJobs.aspx 

Issues found this Andrew's timer job:

• I used the wsp file that Andrew provided and deployed to my customer's MOSS dev environment successfully but got Unknown Error when trying to activate the feature through Site Settings->Site Collection Features UI. The event viewer showed the insufficient permission to write to SharePoint_config database, etc. Then I performed stsadm -o activatefature -id ##### -url http://server/sites/siteName through command and it worked.
• Sometimes changes made to the code were not reflected till the SharePoint timer service was restarted.