Hey Dude,
Just thought I would start a thread that can be built upon with good ideas for future versions by your customers.
I've done a few mock ups too, I'll kick it off:
Facebook and Twitter connect integration into comments
This is done on big popular sites like Techcrunch and Mashable . It encourages more blog comments because people just need to enter their existing credentials:

Ability to change link colours in main post and sidebar seperately
Would be good to have different colours for both

Choice of different link styles within the theme settings

Pages can be shown in thumbnails just like posts
I've been using pages for my portfolio instead of posts because I love the layout of the About Page template. However this means the parent 'Portfolio' page is empty. Would be great to dynamically insert new pages (new portfolio work)
URL entry for RSS icon
This is just for ease of use.
Cufon fonts for Twitter updates in sidebar
That would be a awesome integration
Explaining what new features are in the latest upgrade
I follow the comments on Theme Forest regurly and whenever you say a new version is available I would love to know what new features you've added just so I can check for them and see if they are working correctly.
Just wanted to say this theme is easily the best i've ever seen and if you need any help whatsoever like ideas, graphics, I would be glad to help. You're hard work is defo not going unnoticed