As Janet Theobroma mentioned two new sites around KDE have been launched: KDE-artists.org and open-collab.org.
Both are relaunches of old ideas/websites which already existed for quite a time, but needed to be refreshed since the aims, possibilities, but also because the knowledge of how to address and present things and thoughts has been improved a lot over the time. So what is it all about?
KDE-artists is, like the name says, the place for everyone in the KDE project how comes into contact with art of any sort: if you are an artist, the new site will be probably the site where you spend most of your time, speaking with other artists about what and how to do stuff, what tools you use, which nice and useful tips you have, and so on. Of course the same is true for everyone who wants to become an artist inside of KDE: kde-artists.org will provide you with information, tutorials, standards, themes, guidelines, but also with contacts to other artists or for example tools with which you can work to develop art.
The other new site, open-collab.org, the sucessor of the old Kollaboration forums, is, as the name indicates, completly about collaboration: if you want to share some thoughts about any kind of application – do it there! Especially if you are an end user and want to discuss some stuff, for example together with some mockups this is the right place. You do not have to be a programmer or such to write there, the opposite is the case: open-collab.org is a plattform for people who want to share ideas because they want to see thm but are not able (due to whatever reasons) to implement them. It is also a place to share some good ideas about which you think everyone should know.
On the other hand, if you are a developer, make sure that you keep an eye on that page since it is perfect to contact users and see what they are thinking – feedback is good and can help you keeping an eye on what the users want or dream of. And you can use this forum to contact motivated developers who do not have a project right now: write what you would like to see implemented in your project and what is easy enough to entry the project as a newbie, enthusiasts will read it!
There are also some analysis of Gaps and problems in the FLOSS world documented, and this is something you shoul keep in your mind also – for example because you want to improve your app in this field or you want to prepared for discussions about FLOSSoftware.
And, btw.: the collaboration is not KDE only, one of the main mentioned programs there is inkscape :)