I know, my english is very bad. I read a lot in english and hear english podcasts, but nothing help, because I don't get feedback and therefore I can't get better (or very slow).
Because of family, full-time job and side project I don't have spare time to just sit down and studying language. Only time I have is about 20-30 minutes per day while I travel from my work. Unfortunately, I can't memorize if I hear some sort of audio/video course. I learn from writing and conversations.
What could you suggest me?
One idea is to write some blog posts on mobile (n900, with keyboard and git, yeah) and then push it to github to allow pull requests. But I can't expect that some one will correct me.
Ah, but if you contribute to Wikipedia, someone DEFINITELY will correct your mistakes, AND in a way with rudimentary version control, so you can compare what you wrote to how it looks after the editors swarm in. Find a page on Wikipedia in your language about something that interests you and translate it into English. I personally use this technique to maintain & keep learning my (non-English) foreign languages, and if I can get a response from non-English wikipedia you can DEFINITELY get one from English Wikipedia.