I work as a Java programmer, but C and C++ were always my favourite languages during studies. Unfortunatelly I don't have an opportunity to work with them as often as I would like to. As a result I sometimes get realized that I don't remember something quite important (today example: inherited protected members cannot be accessed in derived class constructors). The other example could be Python and Haskell which I enjoy using but don't use everyday. I got an idea to write my own wiki with easy to forget things (e.g. bash tricks & tips) but I find no sense in writing there everything I can forget about coolest programming languages. I know that the best way would be having a side projects (I want to start working on some C/C++ open source project after graduation), but currently I have to write my graduation thesis and work so I merely don't have time to do this. How do you stay sharp in languages that you don't use everyday?