Love the site, but overall its lacking ajax functionality. For example, it would be nice to obtain the page thru the list of comments dynamically (via ajax) instead of a full page refresh. Also, being able to collapse the boxes on the right to just the heading (which would really clean up the UI). All the users 'settings' (collapsed boxes etc) can be tracked in a cookie.
"Charts Slider": Not sure if this can be provided without incurring 'fees' from chart vendors but I had an idea about posting small gifs of useful charts such as the 'seasonal' ones which would auto-enalge (again, no page refresh) when clicking on them. This could be exapnded for basic charts on /SI etc as well (if these charts can be obtained for free or near free).
One last idea, forcing the user to search a list of phrases or ackronymns hampers useability and understanding of content. How about auto-parsing each post for common acks/phrases (FUBM, EE, Higher Highs, ...) and auto-link them to to provide the description in a popup bubble when hovered (again, ajax data retrieval). This would still work on mobile but only when 'clicked' instead of hover.
BTW, Im a pro at ajax/ecma/jquery/mvc/asp.net so let me know if I can help :)