User nickshertzer over at xda-developers has whipped up a refreshing blue theme for the Dell Streak that includes a custom notification tray with full transparency and custom acid window navigation animations.
The developer recommends using Simple Streak, as he has not tested it on anything else as of yet, but it may work on other ROMs too. He also notes that he is working on custom animations for the notification tray for future releases, so what's available now will continue to improve.
To install the theme, first make a Nandroid backup of your Dell Streak via StreakMod or ClockworkMod recovery. Assuming you have either installed, access them by turning your Dell Streak off then pushing both volume buttons while holding the power button. After this, select option two by navigating with the volume up and down keys then pressing the camera button to select it.
After your backup is made, select "install package from .zip" and then choose the .zip file found at the link below.[xda-developers]