A few comments:
1) Please add one or more licenses so developers can include Akayame in their projects with confidence. A couple of examples:
https://github.com/jquery/sizzle/blob/master/LICENSE
2) The footer and menu are below the fold in my browsers in the Converter and Editor views so I need to scroll to see the menu and "Yet Another Markdown Editor" text.
3) The footer could do with improved styling : text overlaps the border, bullets and links use default styles. Minor quibbles but improvements would improve the professionalism of the site. Image here:
http://autoreverse.s3.amazonaws.com/2011006_Akayame_footer.j...
4) Landing page does not convey to the visitors what the site is about (and"Yet Another Markdown Editor" is below the fold).
5) Adding a page or two with keyword rich text explaining the project ("jQuery powered online Markdown editor") and background ("inspired by other Showdown online Markdown editor projects") could help with search engines listings.
6) Have you considered hosting the code on Github for increased exposure and link juice?