Here is a little list of sites that give you a nice selection of great wordpress theme designs. Hundreds of the highest rated wp themes can be found in these links.. Enjoy! )

• 100 Favourite WordPress themes

• 10 Fresh, Elegant and Clean WordPress Themes (Smashing Magazine)

• 83 Beautiful wordpress themes (Smashing Magazine)

• WordPress themes from Blogging pro (Blogging Pro)

• Best WordPress themes part1 (SilentBits.com)

• Best WordPress themes part2 (SilentBits.com)

• 10 Professional looking WordPress themes (Dailyblogtips.com)

• Part1 Top Ten Best Free WordPress Themes (clazh.com)

• Part2 Top Ten Best Free WordPress Themes (clazh.com)

• Part3 Top Ten Best Free WordPress Themes (clazh.com)

• 18 great themes from Fahlstad (Fahlstad.se)

• 10+ great wordpress themes from Themeporter (Themeporter.com)

• Unmatchedthemes – A nice collection over here )
  
• Twigged.net - 90+ categorized themes (Highly recommended!)