I work on alot of projects and web printing is always a hassle and often people dont want to pay more for a commercial PDF creator. Here is a list of Opensource PDF controls/assemblies:

• ASP.NET FO PDF at SourceForge.net - generates XSL-FO from DataTable to render PDF
• iTextSharp at SourceForge.net
  • Examples and Tutorial: http://itextsharp.sourceforge.net/
  • Also see this article: Create PDF on the fly with .NET and iTextSharp by Valerio Fornito, DoPostBack.com
• PDFCreator at GotDotNet - design PDF document visually using Visual Studio IDE
• Report.NET at SourceForge.net