A few months back, I had written an article on using SharePoint Designer 2007 and InfoPath 2007 to automate business processes. The solution uses InfoPath to create a powerful electronic form, publishes it to a SharePoint form library, then routes that form through a workflow process using a workflow created in SharePoint Designer. Creating your business scenarios in this fashion will let you design true end to end solutions, without using any code, that will save you Tons of time!
This article has finally made it onto MSDN. Check it out here in its entirety: http://msdn.microsoft.com/en-us/library/ff355359.aspx. You can also check out the video/screencast for this whole process here: http://www.sharepoint-videos.com/automate-business-processes-using-infopath-forms-and-sharepoint-designer-workflows/