leafleting is one of the best forms of marketing (on a ROI basis). The trick is to make sure you hit the right demographic.
you mentioned 'computer fairs', I am not sure if that would be the best place to target, although it depends what product you were targeting of course.
if you are trying to get businesses individually interested, then certainly that is not the place.
Damn I could write an article about this, because as i am typing I am contradicting myself with thoughts like " hang on Old Welsh Guy, that isn't exactly true, because leafleting a computer trade fair with a leaflet about reselling packages and a high level of support would been Ideal situation"
Ok so deep breath and a statement, here goes.
Leafleting is probably the best offline method of marketing reactively! BUT it depends on the the time old FACT of the 3 basic rules of the perfect marketing campaign
1. Right message
2. Right person
3. Right time.
If you get those threee elements right, then you are marketing, get them wrong and you are advertising!
OK I just decided I need to write this up as an article LOL