Actually I loved the beginning of the welcome message (thank you for taking the time on your busy life ...) but passed a few sentences I scrolled down to find the link.

On the feed page, I think you could reduce the text on the sidebar. I dont care about the welcome message, if I'm registered why do you explain me the website again I should already had understand what Sparkmuse is about. I would delete that paragraph and replace it only by the "Create Spark" button (make it big and colorful, I didnt saw it the first time I saw this page)

You can also reduce the "We want feedback" block maybe you can install uservoice or something.

On the spark page the solution appear 2 times at the top of the page and on the sidebar. Why ? Maybe you should put the question and the solution at the top of the page like Quora/Stack Overflow or other discussions board.

Again it's only my PoV. You made a great job .