Logarithmic slider: http://mathematica.stackexchange.com/q/28457/5478
Would something like this help?
Manipulate[ Log@L, {{L, 10^-9, Style["L", FontSize -> 16, FontFamily -> "Times"]}, 10^-11, 10^-7, ControlType -> Slider, ImageSize -> Medium, Appearance -> "Labeled"}]
