Hi Onno,
Congrats on being a semifinalist! I was an ETA to Germany for the 2010-2011 cycle and while some other ETAs did go on to work as teachers, you're definitely not limited in that regard. I worked in education for a few years but recently finished my MA in PoliSci and am working in international development. Other ETAs I know from Germany have pursued varied careers (educational policy, public policy, law, etc.) What really matters is 1) how you use your time as an ETA in-country, what activities you pursue, to what extent you make an effort to integrate yourself and 2) how you use the lessons you learned from your ETA once you get back to the States (or wherever you end up). Working in the fields of women's rights and/or especially education is very doable and realistic after having been an ETA. Good luck!
(Also, feel free to keep the Clinton Fulbright in mind afterwards if you're interested in international public policy. That's what I applied for this year- still haven't heard anything back yet though.)