Hello... I've got a dark theme I put together after The Dr. Nic Williams TextMate theme stopped working with a recent update of Aptana. I'm by no means an Aptana expert (total n00b actually), but hopefully other people who were upset to lose the Dr. Nic theme will be able to make use of this one.
You can download it from
http://www.dave-dean.co.uk/aptana/aptana_prefs_dark_theme.zip
You will need to import the three colourisation files in the relevant parts of the Preferences dialog for ERB, HTML and CSS and import my preferences file for Ruby colourisation from the File | Import menu. (Other than some colour changes, my preferences aren't changed much from the defaults).
Note: I haven't found a way to properly colour symbols in ERB - to my mind, this should really take colourisation from the Ruby preferences. Also, bear in mind I only use Aptana for Ruby on Rails development - I don't know how useful this theme will be for you other peeps.
Feel free to tweak to your hearts content and improve on it.
-Dave