Most desired programming skills in a startup?
subwindow: All of them.  Or, none of them.Basically, you need to be able to do everything.  From graphic/ui design/css, to html, to the MVC stack, to the database, to the system administration and the networking.For a startup, being a jack of all trades is far, far more valuable than a specialist.  How much use will a startup have for JUST a programmer that won't touch the database or the servers?  If I'm hiring a developer who is ostensibly going to be coding in Rails all day long, their ability to do design and database work is just as important (if not more-so) than their actual experience in Rails.Take a look at the stack above, and learn more about whichever one you're least comfortable with.  If you've never touched photoshop before, download their 30 day trial and at least familiarize yourself with it (good frequently-used "beginner's" task: making a transparent PNG of something like an arrow).  Never set up a linux system?  Clean out that old windows box and install Debian (server) and set it up as a file system.Rinse and repeat.