Catrice Waterproof Top Coat has been my ally this summer. It is the perfect top coat for your favourite mascara and, since it is transparent, you can also use it as an eyebrow fixer (although I am not sure that it is actually meant for this purpose, but for me it works!).
I bought it at a wonderful store that exists in Germany: dm - where you can find make-up, perfume, toiletries, girl products, cleaning materials, etc. It is an absolute girl paradise!