Wikitravel is a Wikipedia-style online encyclopaedia exclusively about travel that covers over 25,000 destinations around the world. Since it’s a wiki, it’s created and edited by its users rather than paid professionals, which means anyone can chip in with some useful information.
Travel guides are more useful in a pocket than on a computer screen though, but accessing the internet when outside the UK can be a costly business, thanks to the high cost of data roaming with mobile network operators.
Fortunately, Wikitravel is also available as a complete download, which means the whole thing can be carried on a smartphone and kept as a handy reference for use without internet access.
There are various versions of the Wikitravel site available for offline use. Oxygenguide is free for Android, Amazon Kindle and Nokia smartphones weighs in at a mere 53 megabytes, but dispenses with images.
iTravelFree is more versatile in that includes both images and OpenStreetMap data for getting around, but the free version only allows data for one place to be downloaded at any one time. Downloading all of Wikitravel requires the paid app, which costs £1.99 for iPhone/iPad and Android.