it would take a while, but I could see if I could look out videos of her speech progression if you want?
I found some old film of her when she was about 3 the other day - I could hardly understand a word of it, when I know for a fact (and there is evidence of it in the film) that I understood everythign she said at the time. the only comprehensible bit was when she sang 'bbbeeeeeee bbeeeee sssseeeeeeeee raaaaaadioooooo tooooooo' 
(no prizes for guessing what I listen to in the car!) with massive over enunciation and exaggerated facial gesture.
she has (completely off her own bat) long used any reflective surface to help her - when she was little it used to be to practise the shapes her mouth had to make for certain sounds - she would study us intently when we were talking and then practise moving her mouth that way (grossly over exaggerated at first, then refined down to fine motor movements). she can find a relection anywhere - a window, the laptop screen, actual mirrors, her cutlery at mealtimes etc. it can be a real hindrance, as these days she practises conversations rather than speech sounds - leading to her talking/singing to herself all the time - it's eaiser than talking to people who may say the wrong thing in reply!
she now practises mini conversations, using appropriate facial gestures - downturned mouth for sad, raised eyebrows for surprise etc.
dd1's speech really came on after she went gf/cf - well, her communicative intent did - see above for her speech refinement!
she is 8 now, and I would say she has been easily understood by others (clarity of speech wise) for a couple of years now, probably since she was 5 or so.