Phoster is described as 'This is a user-friendly application to create stylish posters and various invitation cards'. There are three alternatives to Phoster for iPhone, Online / Web-based and Android. The best alternative is Fonta, which is free. Other great apps like Phoster are Cymera (Freemium) and Glogster (Freemium).
Fonta allows you to create unique images with special effects. Add text behind a photo, masking (put your photos inside text), collages, frames, vintage filters, color layers, artworks, 3D geometric shapes, blur effects, etc.
Cymera is easy and All-in-One app for your photos and get the perfect look you desire. Features - Album Create and share photos through private albums with your friends. It will be one of adorable place to feel the pleasure by sweet or fun retouching!
Glogster.com - Poster yourself - Make your interactive poster easily and share it with friends. Mix Images, Text, Music and Video. It is fantastic! == Educational version is also available at http://edu.glogster.com/