I really like the backoffice GUI of Umbraco. Its easy to work with and gentle on the eyes. However I suppose there is always room for minor improvements. For instance I think that the tray icons could be a little more saying, the texts could be less blurry and sometimes a translation of the text is needed. Therefore I usually change the tray icon file and thought I would share it. Its a tinie tiny improvement (if even that) but it takes 10 seconds to do.
Just download the appropriate language tray icon file and overwrite the existing tray icon file in /umbraco/images/tray
If you need support for another language, you can download the Photoshop file and make your own. Please share it here.
The icons I have used are the Silk Icons, which were created by Mark James of FamFamFam.com and licensed under Creative Commons Attribution 2.5 License You can find the rest of Silk Icons here: http://famfamfam.com/lab/icons/silk/