MakeUseOf.com had a posting recently about PDFHammer, yet another PDF utility. The benefit of this one is that it is all online.
PDFHammer is a web-based application that allows you to merge and rearrange PDF documents online. It’s free, extremely easy-to-use and runs directly from your browser. You don’t have to register either, just upload PDF files and start arranging the pages in any order you want. Once finished, use the “Export Final PDF” button to download ready PDF file to your PC.