I actually designed many Invision Skins for swish-db.com but since Invision Powers Board fixes security bugs and asks to upgrade so quickly, I was fed up with adjusting skins all the time, so at the end I kept their default skin. And also I dont have previews of those skins, however the most recent 2 phpBB skins are below

The GimpTalk Skin (phpBB3)
Gimp is an Opensource software similar to Photoshop, you can visit this link to see the skin live : http://www.gimptalk.com/forum

Xitalk Forums phpBB 2

XiTalk is a revenue sharing community, that helps all the contributors earn money through Adsense at the same time. See the skin here : http://www.xitalk.com/