I'm having my (dutch) Ning site now for about 1.5 years.
I've been changing some small things and some bigger things in the design and I'm looking for your point of view as an outsider to critic the site.
It's hard for me to do for my own site since it's all about first impressions!
Give it a go if you please: http://inventorwizard.ning.com/
I am relatively a newbie to Ning, but want to help with my limited experience and knowledge, so here I go...
I can't read Dutch, but with Google translator help I could overall understand your site's content. (I later saw that you have Google translate on your Wibiya toolbar: cool!) Design-wise I favour lighter and brighter colours, but I think your site's dark background design goes with the nature of the topic/members... I like the combination of blue and orange (the favourite colour for the Dutch and me!)... The social media icons on the left are also nice.
I quite like the dropdown menus you have created for the "Beyond my NAV" and other sections. This allows quick access to various options/pages for members and should promote more interaction. I also like the scrolling news feed from your main site: I'd like to do the same on my site. I specially like your "Manual" page under "About" section: this should help members (esp. new) to understand how to use your site.
Overall, I like the way you have integrated your Ning site with your main site: lots of links go to your main site, while the focus on the Ning site is on interaction, through the "Latest activity" and "Forum" sections on the main page... Also, you have news feed and other content from your main site appearing on the Ning site. I also saw your forum content appearing on your main site, which should encourage your main site visitors to join the Ning site.
What could be improved? I think you should try to reduce your right column content, as on some inside pages it is way too much longer than the main column. I know we all want to maximize the ad revenue opportunity, so would like to have ads appear on all pages, so the ads should be part of the common features that appear on all pages. But you could move the videos to the main column, or make them appear only on the home page...
I prefer blue for links (good web practice) so glad you're using that colour, but the blue on black on the top navigation menu makes it difficult reading (colour-blind people will have more difficulty with that). Also, the dark orange-on-black style for section headers (like "Inventor wizard gallery" etc.) is a bit jarring to my eyes. My suggestion would be reduce the dark grey/black in the headers in the main content area: this would make the content stand out more prominently against your dark page background.
Hope these comments from a quick look help you. If you have a moment, feel free to visit our site TheSouthReports.com and share your comments here. We are redesigning our site, so are looking forward to critical comments, and will be grateful for any feedback, but there is no obligation at all, really! :-)
Good luck with your site!