sql
html
php
css
c
ajax
python
database
linux
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android
ruby-on-rails
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objective-c
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php5
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jsp
postgresql
There are some good html/css example here: http://www.alessioatzeni.com/mac-osx-lion-css3
and a few older examples here: http://www.therestartpage.com
There's a nice open sourced one built using JQuery called elFinder. Take a look: http://elrte.org/elfinder