The Digital Photography School website has a tutorial up which claims to make digital photos look like Lomo images.
(Tutorial link found via Digg.)
Lomo cameras are principally cheap toy cameras that suffer from mild light leak, giving the images a curious ghostly quality.
You can find out lots more at www.lomography.com.
Until recently they remained popular in China, particularly the Holga clone.
Lomo, or Leningradskoye Optiko Mechanichesckoye Obyedinenie to give it its full name, continues to craft high-end scientific lenses to this day, as well as supporting users who have turned to their cheap cameras after falling in love with the curious light flaws.
The tutorial linked above will help you make images taken on a £10,000 Canon digital camera look like they were shot on a £5 camera with a plastic lens.
Or you could just go and buy a Holga or Lomo camera on E-Bay for a few quid and enjoy the delights of low-fi photography. Personally I recommend the Lubitel twin lens reflex, which can be had for next to nothing these days. I also recommend the Woca, which is basically a Holga with a glass lens.
Both the Woca and Holga, as well as the Lubitel (obviously) use medium format film, which is worth investigating in its own right, particularly in these days of digital photography.