Billig telefonieren - (translation: cheap phoning), is not the only thing this german startup offers: the website includes very nice jQuery tabs at the bottom of the yellow content box along with various other effects like ajaxed form validation and a sliding login button.
Slick tabs with an interesting slideup/slidedown motion. You should also check the sleek transparent login form, that fades in as soon as you click the login button.
The tabs lack a stylish fading transitions like the aforementioned examples, but I really like the big icons, since they are really begging for a click =)
A good example if you want to use your tabs with some text instead of icons
Sliding Content - Transitions Everywhere
The redesigned monofactor website shows recent portfolio entries in a neat contentslider.
Alex Buga, self proclaimed Webdesign Superstar, slides his recent entries horizontally. Be sure to check out his neat main menu as well. Last but not least the site makes heavy use of ajax.
This one is already known by everyone and their grandmother but always a good site to draw inspiration from, so no way this site could be ignored.