I saw blog which has nice formated Google Adsense ads, but I don't know how to generate them. Here is a screenshot: http://imgur.com/U0mzk (sorry for plain link but I'm too fresh here to use img tag )
Is it text link format or what?
That's a normal Google Adsense advert but with some nice colour selections.
Back in the day, Google didn't have many formats of ads. There were no image ads and no Ad Links (small or think text boxes). The only ads were text ads in banner shaped boxes.
One feature Google introduced early on, was the ability to style the text in the ads so that the matched the look and feel of your site. When you create a text/image ad in Adsense you have the option to choose from a selection of template colours but you can also set your own choice of colours. In the case of your screenshot, they have opted for some nice purples and blues which go well with the rest of the site design. You can also adjust the font sizes a little, change the font-face, and also set rounded corners on or off.
It's worth noting that Google Adsense TOS says you shouldn't make the ads look exactly like the text on your site. There should be some distinction so as users are not confused and can identify clearly what is an ad and what is not an ad. Additionally, some marketing people say that you should make your ads contrast with the site and stand out. This apparently gets you more clicks on the ads. Though it also makes your site look naff.