For all of you lucky people that own an iPhone (or Android equivalent) your first port of call will most likely be the ubiquitous Instagram (with Picplz being a close Android substitute until Instragram proper lands).
If you’re after something a touch more destructive then there’s Decim8.
Good for that damaged vcr flavour or artifacty wierdness.
I’m not one of these lucky people so I have to use other means.
My current faux retro set-up is my lovely Canon 60d (get one) with a Holga reproduction lens from Hong Kong (£15 on ebay).
The other option is a Lomography Diana lens with appropriate adapter.
More expensive and you lose quite a bit with the digital crop factor, but still some charming results.
Or you could just get a proper Lomo camera, but y’know, film and stuff.
Now off you go, get shooting.