Well you can do the Following:
1> Beta Test if you wish
2> Use Savvy Journal Skins
3> Admin up to 10 Groups
4> Use Fancy Custom widgets
5> Access more widgets to spruce up your Profile
6> Get an Automatic 10% Off deviantART Purchases which can even be combined with other special offers or sale
7> You can customize your page and galleries with CSS if you know how or get another user ta do it for ya
If I missed Anything #
PremiumMembers is a good group to check out