I am searching for an internet platform to setup a forum where customers can publish and election "ideas" (i.e., plans in regards to a subject).

More particularly, I want something similar to Wordpress Ideas.

Anybody knows any opensource software that could assist me to?

xox

Well, WordPress ideas is run by bbPress + plug ins + custom theme.

You most likely could spend a while and accomplish an identical setup with a few forum software of the selecting, a voting wordpress plugin, plus some custom theming.