Looks like Jan (http://weblogs.asp.net/jan/) has been doing some interesting stuff....going to keep my eys on this GotDotNet workspace and see what drops in....

Workflow Lite for SharePoint

Generic configurable document library event handler that can be used to create simple workflow and approval scenarios in Windows SharePoint Services or SharePoint Portal Server 2003.

http://www.gotdotnet.com/Community/Workspaces/Workspace.aspx?id=c07f64e8-8229-49a1-b160-b24c89122894="/A">