http://cmsmart.net/magento-extensions/v-admin-magento-extension Replace the default theme of your admin cpanel by using V-Admin theme.

1. V-Admin Magento Extension
Replace the defaulttheme of youradmincpanel byusingV-Admintheme.
 Installation Instructions
1. Disable Compilation
Log into the Magento Admin Panel and go to System, Tools, Compilation. Then, disable the compilation, this will let you run
the compilation process again.
2. Install the V-Admin Extension, via Magento Connect
o First,getthe extensionkeyfrommagentoconnect
o Then,go to System,MagentoConnect,MagentoConnectManagerand use youradminaccount to loginagain.
o Once you are loggedin,paste the extensionkeyinthe fieldnamed"Paste extensionkeytoinstall",thenclickInstall.

2. o Afterinstallation,clickthe Proceedbuttonandthe V-Adminextensionwill be installedautomatically.
3. Clear Cache
Go to System, Cache Management. Then clear the stored cache.
4. Re-login
After clearing the cache, logout and then log back into the Magento Admin Panel. After this step V-Admin will be successfully
installed and ready for configuration.
Configure your store
To complete the process, you will need to configure your store.
1. Go to System, Configuration. Then, from the left sideboard, click V-Admin theme under VNECOMS section.
2. Then, expand the General section.
3. Set the Enable V-Admin Theme field to "Yes".
Congratulations! After completing this last step, you will see your admin cpanel theme is changed to V-Admin theme.
With black base color and great button set your website will look better.