what is the most effective offline marketing you have experienced? (calling, business cards, flyers, etc)
Depends on what you are advertising. If i were to promote a concert or event at a local bar I would put up colorful and eye catching posters in the local mall, maybe talk to the taxi drivers and ask if they wanted to spread the word about Band X playing at place Y on Z.
I didn't do too much offline marketing, but when I do I get the best success with flyers in the right places.