Danland is clean, simple, elegant, and beautiful Drupal theme by Danetsoft, developed by Danang Probo Sayekti, and is inspired by one of website design by Maksimer.
Danland demo site (we turn off all jQuery plugins).
Danland is very suitable for all types of websites; from corporate site to blog site, and it works perfectly in every browser; tested in IE6/7, Opera, Safari, Chrome and Firefox.
This theme includes an image slideshow or photo slideshow feature on the standard installation, where this feature is still rarely included in the standard installation of Drupal themes.

Update - please upgrade to the Sept 3rd development snapshot of this theme and Fusion, along with the new dev version of Skinr

Light Fantastic is is a theme developed for the Google Summer of Code 2007 by Buddhika Amila Sampath. In the summer of 2009 Brauer Ranch Ltd, Co. sponsored conversion of the theme to the new Fusion theme system. The conversion was done by TopNotchThemes.

mpFREE

By Mehrpadin on the 17th of December, 2009

mpFREE is a premium Drupal theme. See it in action

Overview:
Highly-customisable.
Over 20 regions.
W3C valid xHTML\CSS design.
Compatible with all major Web browsers (IE, Firefox, Opera, Chrome, and Safari)
RTL (Right-to-left) language support.
Built-in style for (At the 'Header' region).

Addari

Addari is another clean theme contributed to Drupal from Worthapost. This theme targets those who want cleanliness and web 2.0 mixture for their Drupal based website.

Features

• Rounded Glassy corners of container.
• 7 Block regions which are Big right sidebar, Right sidebar, Left sidebar, Header, Footer, Content Top & Content Bottom.
• Pre-Made Search block (just enable search module and set appropriate permission).
• Mission block positioned on right portion (See in Screenshot)
• Attractive comment section.
• Optimized background images that loads very fast.
• CSS based design without tables.
• Cross browser support including IE6

litejazz

LiteJazz is a GPL theme by RoopleTheme. It features 3 color styles, 12 fully collapsible regions, suckerfish menus, fluid or fixed widths, easy configuration, and more. To see LiteJazz in action, visit the LiteJazz demo site.

LiteJazz Version 1.7 is largely a ground-up rewrite of the theme. Numerous things have been added, changed, or fixed. Here's a summary of the major changes:

Aboutpeople

Aboutpeople is a 3 column layout theme with a wide image banner and a "top-tabbed" primary-links system.

Main features

• Flexible 3 column system
• support for search box and avatars

Pixture

Pixture theme is a original recolorable theme for Drupal 5.x and 6.x

Key Features

• Recolorable theme (like Garland theme) with color module.
• Many original color schemes are prepared.
• Supports both 2 column and 3 column layout.
• Supports both liquid and fixed width layout. It can be easily switched and configured at the theme setting page.
• Simple, easy to read, suitable for a blog.

It is tested with Firefox, IE-7, Opera and Safari.

Genesis

Genesis is an standards compliant, accessible and semantically rich starter theme for Drupal. Genesis is easy to theme yet extremely flexible, giving you endless theming possibilities. Genesis makes building a standards compliant accessible theme easier than starting from scratch.
A few sites seen using Genesis:
http://design.acquia.com
http://www.myappleguide.com
http://laptopblog.gr
http://adaptivethemes.com
http://www.drupalcampireland.org
http://www.calthorpe.com

NewsFlash

NewsFlash is the latest GPL theme by RoopleTheme. It features 7 color styles, 12 collapsible regions, suckerfish menus, fluid or fixed widths, built-in IE transparent PNG fix, and lots more. To see NewsFlash in action, take a look at the NewsFlash demo site.

NewsFlash Version 1.6 is largely a ground-up rewrite of the theme. Numerous things have been added, changed, or fixed. Here's a summary of the major changes:

Drupal 6 Compatibility: NewsFlash 0.16 is now available for Drupal versions 5.x and 6.x.

Simply Modern Theme

Simply Modern is a table-less, CSS driven design sporting an advanced feature set.

Some of the key features are as follows:

• elements via CSS for all layouts (no tables)
• 14 User Regions
• Drupal 6 functionality
• Tested in IE 6, IE 7, Firefox and Safari
• CSS and XHTML valid
• Upload components from ThemeSettings API
• Custom Page Background
• Custom Mast Head
• Custom CSS File
• Five preset color options

RootCandy

RootCandy is a 3 column theme focused on administration section.

• Supports node/add /edit pages
• Re-colorable
• Icons
• Top navigation by role
• Simple dashboard
• 3 column fluid or fixed layouts
• Rootcandy dark sub-theme
• Icons in compact mode
• Sliding region

To know more, read the documentation -> http://drupal.org/node/325933

Marinelli

Marinelli is a 3 column, tableless layout theme with a wide image banner and a "top-tabbed" primary-links system.

Here you can try a live demo

Sorry but 5x version is no longer supported
I'm currently working on the 7x version which will include lots of new features and general improvements, so 6x development is currently stopped

Acquia Marina

NEW: Port of this theme to the Fusion theme system with tons of new features is up in the 3.x branch! The Fusion base theme and Skinr are required for the 3.x version.

Acquia Marina is an advanced theme developed by TopNotchThemes in partnership with Acquia for their Drupal distribution. It contains the same kinds of features you'll find in our other Drupal themes.

Features - 2.x

• 1, 2, or 3 column layout
• Selectable fluid or fixed width layouts and font stacks
• 15 collapsible block regions

Zen

Zen is the ultimate starting theme for Drupal. If you are building your own standards-compliant theme, you will find it much easier to start with Zen than to start with Garland or Bluemarine. This theme has fantastic online documentation and tons of code comments for both the PHP (template.php) and HTML (page.tpl.php, node.tpl.php).