sara cannon

Twentyten is the default theme for WP 3.0 and has beautiful CSS for its menu system. However, if you wanted your menu to drop down in IE6, this does not occur. Use this plugin to make that happen using the jQuery built into WordPress. Many people don’t care about browser compatibility back to IE6, so this plugin is for the few that happen to.

Twenty Ten IE6 Menus

Use this plugin to make the main menu in the twentyten theme drop down in IE6. Perfect for Child Themes.

toddhalfpenny

Makes your TwentyTen themed site have a responsive and fluid layout. Making it ideal for for viewing across a whole range of devices and screen sizes (i.e iPhones, Android, iPads). 
Uses CSS and media queries to enable the fluidity and responsiveness.

Responsive TwentyTen

Makes your TwentyTen themed site have a responsive and fluid layout

Twenty Ten IE6 Menus vs Responsive TwentyTen