Readdle has rolled a PDF converter for iPad. While iPad can natively read PDF files, it does not allow the user to create PDF on the iPad. In other words, it lets you transform any file stored on the iPad into a PDF document whenever you need it. It allows you create PDF files from email attachments, iWork, Office documents, Clipboard content, documents on dropbox, iDisk and contacts.
I think it is a perfect companion for me. Many-a-times, it happens that I want to save something for my future reference and that is where PDF convertor / creator is going to come handy. Costs 7 dollars. [download here]
For reading PDFs, I personally use GoodReader. You can read its review here.