I've got a suggestion : it would be useful to be able to delete own contribution.
Just an exemple (real based) : i've juste made a small contribution, send to language pack maintener, and i realise it can be improved. I'd like to be able to delete my contribution, to submit a better one. Of course, language pack maintener should receive a message to informe him that a contribution has been deleted!
And this possibility would be allowed only before the maintener comes to see/validate the contribution!