I ve worked on my free time on opensurf algorithm(http://www.chrisevansdev.com/computer-vision-opensurf.html). It's ported from c++ to full as3, so it's still quite slow... Here is the link to the github repository, It would be cool if someone could speed up this process ! Furthermore I have few doubts about my matrix conversions... (in FastHessian.as).
Sources : https://github.com/samuelgirardin/OpenSurf-AS3-Algorithm .
For the moment I continue with alchemy to improve perfs.
You can test it live here by clicking on the view demo button above.