Professor Jonathan Raper - 'The Digital Geographer' blog
isblogs.soi.city.ac.uk/staff/raper/

Andrew Grill - 'London Calling' blog
www.andrewgrill.com/blog/

The LBS Zone
www.lbszone.com/

Camineo - the digital guide for tourism
www.camineo.com/index-en.html

Traffic Master UK
www.trafficmaster.co.uk/home.php

AdMob - Mobile advertiser
www.admob.com/s/home/

'Madison, we have lift-off' - The Economist, 2008
http://www.economist.com/business/displaystory.cfm?story_id=12685528

Wikipedia
Location Based Services | Location Based Advertising