PrimePrint is described as 'Directly print websites, documents, E-mail, photos, and more to a wide range of Wi-Fi printers with ease. Choose from a large variety of layouts to suit your specific needs. Design and create fun and original printouts simply and easily!'. There are three alternatives to PrimePrint for Mac and Windows. The best alternative is Printopia. It's not free, so if you're looking for a free alternative, you could try handyPrint.
Use AirPrint to print to your Mac's shared printers, from your iPhone or iPad. Run Printopia on your Mac to share its printers to your iPhone, iPad or iPod Touch. Add unlimited virtual printers to save print-outs to your Mac as PDF files.
handyPrint, previously AirPrint Activator, is a small application that will enable AirPrint, a hidden feature to allow your shared printer to be visible on your iOS 4.2+ devices, in Mac OSX 10.5, 10.6 and 10.7.
Presto, previously FingerPrint, enables AirPrint on any printer. All of your printers are displayed in an easy to read list in FingerPrint's main window. You can then select which printers you want to enable for AirPrint.