Well the title says everything, if you got one and you aren't sure or just don't know what games you can run on it, imma list some here so you can have an opinion in case you wanna buy one of these small thingies :)

Starting with the latest MMORPG's tested on Asus EeePC 1000HA,

1. Battle of Immortals

this one runs pretty smooth, even in dungeons that has tons of mobs, when you see more then 30-40 players on the same spot RUN! :) otherwise it will be very laggy for you to play :) other then that it works like a charm!
btw! this game is amazing so don't pass without playing it :)

2. TLBB aka Dragon Oath - EU version.

yet another nice one, but this one works much smoother then the first one

3. Karos Online


4. Florensia Online


5. KunLun Online


6. Zu Online


7. Tales of Fantasy


8. Flyff Online


9. NeoSteam Online


10. Grand Fantasia


there are just a few of the games that are running nice on this little & cheap netbook, have fun hunting for more or just playing on it :)
PS: these games run on the default netbook, with no overclocking or RAM upgrade.

So yea it can be used as an gaming rig.