As you know that netbook have some limitation in hardware compared to notebook or desktop computer. Usually, Netbook can be used to surf the Web, compose e-mails, do light office tasks, and play music or videos. Due to that limitations, a linux distribution which optimized for that limitation are required in order the function and usage of netbook still can be used especially in screen resolution limitation and less processing power limitations. Here are some linux distribution / distro which optimized for netbook :
Ubuntu Netbook Edition
Ubuntu Netbook Edition was formely Ubuntu Netbook Remix is a Ubuntu distribution which optimized for netbook. Ubuntu Netbook Edition brings all the advantages of Ubuntu to netbook with the interface called Unity, an innovative user interface super-optimised for smaller screens. With Unity, the GUI is very nice and suitable for netbook screen.
You can find the detail of Ubuntu Netbook Edition here
MeeGo is distrubution which come from combination (merging) of Moblin and Maemo. MeeGo integrates the experience and skills of two significant development ecosystems, versed in communications and computing technologies. The MeeGo project believes these two pillars form the technical foundations for next generation platforms and usages in the mobile and device platforms space.
You can find the detail of Meego here
Jolicloud is an Internet operating system which is designed to run on relatively low-powered netbook computers. Jolicloud transforms netbook into a sophisticated web device that taps into the cloud to expand your computing possibilities. The web already hosts a significant part of our lives like mails, photos, videos, and friends are already somewhere online.
You can find the detail of Jolicloud here