There is a community repository for MeeGo netbooks. You can find it in the wiki or the forum at www.meego.com.

Then there's the Intel AppUp store on the few netbooks that actually come with MeeGo preinstalled. If you want to use the AppUp store on a vanilla MeeGo, you need an Intel Developer Account and get it from appdeveloper.intel.com.
However, the quality of the apps in Intel's MeeGo AppUp store as well as the store client software itself is the worst imaginable. You wouldn't miss anything important without AppUp.