No flash plug
Enter 'The Swipe' which is basically a pice of card covered with a micro-fibre cleaning cloth - the clever bit is the gentle bend at the business end which allows you to easily slip it under each string and give it a good clean.
Def. one of those 'why didn't I think of that' inventions ;-]
Cheaper than a set of new strings, and it should make one last a bit longer. You'll no doubt be seeing them pop up in your local music store, or check 'em out here:-