Langhorne Slim at Cameo Gallery (09/29/09) Photo: Jon Klemm (more) Apr 24 Emeli SandeBuy TicketsAmex presale begins:Wed, 03/21/1212:00 PM Music Hall of WilliamsburgBrooklyn, NY08:00 PM Buy TicketsAmex presale begins:Wed, 03/21/1212:00 PM May 4 Pierced ArrowsBuy TicketsAmex presale begins:Wed, 03/21/1212:00 PM Mercury LoungeNew York, NY10:30 PM Buy TicketsAmex presale begins:Wed, 03/21/1212:00 PM May 5…