Little black dress

Or probably not so little! I've got a 'do' coming up next weekend (actually possibly 3 before Christmas) that I need a smart dress for. I'm unlikely to get to the shops before then so am thinking about ordering something online but I do hate trawling the internet sometimes - there's just too much choice. Has anyone seen or bought anything lovely in the shops recently? Knee length, black, bit of sparkle/ruffle?