I'm just working on the project where I need to generate barcodes and display them inside SharePoint. I needed some component which would generate these barcodes and I wanted it as SharePoint solution (wsp file) which would make the deployment easier and administrator friendly. I decided to develop a web handler (ASXH file), all you need to do is to call the web handler and pass all information (i.e. barcode data) as URL parameters.
Here is the example of generated barcodes:
Visual Studio 2010 project is available here. You'll need WSPBuilder extension to create the wsp package and Free 3 of 9 font installed on the server or dev machine.