Living in London, it had never occurred to me to do a top tips for visiting my City- however, seeing the lovely Brooke's post over at http://www.worldofwanderlust.com inspired me to share my tested and tried tips for a weekend full of fun in the capital.
Head straight to Borough Market for a wander (and breakfast). Found under the arches of London Bridge this market is a haven for foodies and caters to every taste under the sun.
In the evening I'd totally recommend a treat-yourself-meal at Rules, the oldest restaurant in London. They do a great fish and chips - a staple English dish. After dinner I suggest you get yourself to the Hippodrome Casino - catch a live Burlesque show, smoke some shish if it's your thing and definitely have a cosmo (or two) at the mezzanine bar, watching the gamblers below you. You could always catch a West End show if you fancy a bit of culture (however the only true cut price booth in Leicester Sq is TKTS so beware of other places charging a premium).
Have a leisurely breakfast at The Breakfast Club - they have a few dotted around London, perhaps start in Hoxton. From there wander either to Brick Lane or Spitalfields Market, both easy walking distance. Brick Lane is famous for vintage shops (and curry houses), Spitalfields houses an eclectic mix of stalls, restaurants and quirky shops. They're both worth a visit at some point.
If you have any energy left after that you could head for a British afternoon tea at The Ritz, Claridges, The Savoy or I've recently discovered an Afternoon Tea on a London red bus which looks like a great idea to eat cake and see the sights all at once.