At all:

What´s about polls where all members can vote (one time per poll) for or against something?
(For example what could be changed or so)

Hmmm, not a bad idea! Talk to Jace about it.

Be specific....

 I mean a kind of a extra page, where every member can put something what he want to do other or change and all the members can vote for or against the idea in a regulate time.

There is a Suggestion tab at the bottom of the forum menu under the heading "General".  A member could begin a poll and then other members could vote by posting their individual responses.

Yeah of course I know that, no I mean a kind of page of ideas for changes of the side (LG) and not for the lanterns for maybe a little better ambiance. For example what should stand in the general statistic of the members and what not.
Of course I don´t have to decide about this and that but it´s only an idea from me and I believe an other member proposed this a long time before.