Create PDF Files on the fly with C# and PDFSharp

There are a lot of open source libraries available for this. the best one I found is the PDFSharp, and its totally FREE.
Here is a little introduction about PDFSharp:

• PDFsharp is the Open Source library that easily creates PDF documents from any .NET language.
  
• The same drawing routines can be used to create PDF documents, draw on the screen, or send output to any printer.
  
• It can use either GDI+ or WPF.
  
• It includes support for Unicode in PDF files.
  
• It also includes MigraDoc Lite which brings you all the high-level functionality not included in PDFsharp.
  

if you want to download pdfSharp Library visit the site below:
http://www.pdfsharp.com/PDFsharp