Image2PDF a simple WPF application developed in C#. I've used iTextSharp library to create the PDFs. It's a great open-source library with lots of capabilities.
I've also started using SyncFusion WPF control library recently. The entire control suite is free of charge (which is always a great price!). It has a Wizard control which I decided to go with. I think using a wizard and is cleaner UI instead of dumping every control on one window.
As you might expect you provide the list of input images, re-order them if needed, choose the path for the output folder and go!
Step 1: Select input
Step 2: Select output
Step 3: Go!