Are there any Stackoverflow-application for cell phone, with which I can
- ask a question
- write a answer
- do other things, vote up-down
If there is, can you give a link to download it to mycell phone ?
my cell phone is nokia N80
As balpha mentions in his comment, the API is read-only, so there are no apps that will let you post questions, answers, or vote on posts.
On the upside, the mobile interface on the sites themselves is pretty decent. I recommend just using your phone's web browser to use the SE sites.