Posteriza is described as 'The program is easily intuitive to use. Anyone can use it to design good looking posters in minutes'. There are nine alternatives to Posteriza for Windows, Online / Web-based, Mac and Linux. The best alternative is Rasterbator, which is both free and Open Source. Other great apps like Posteriza are pdfposter (Free, Open Source), Posterizer (Free), Block Posters (Free) and ProPoster (Paid).
The Rasterbator creates huge, rasterized images from any picture. Upload an image, print the resulting multi-page half-toned pdf file and assemble the pages into extremely cool looking poster up to 20 meters in size.
This requires the installation of Python and pyPDF. Out of the gate, the script does not provide for image overlap, however there is a patch that does fix this. The patch requires replacing 5-6 lines in 3 files and adding 2-3 new ones, its very easy.
Posterizer's free online rasterbator allows you to create posters larger than a standard page, using the tiled printing method. It will rasterize any image and output files that can be printed at home and reassemble to the original image.
Ever wanted to create your own poster? That's exactly what Easy Poster Printer can do for you. You don't even need a special poster printer! - Easy Poster Printer does the job with a regular every day printer.
PosterPrint can take a document created by any Windows printing application & prints it on several standard sheets of paper using any printer. If a poster doesn't fit into one sheet of paper, print it on several and glue (or tape) them together!.
This very simple script requires the installation of Python, Python imaging and ImageMagick. Its crying out for a web front end and maybe generalization Perl and PHP versions as well as a front end. Nevertheless I tested it out and it does work.