If they come to your table or such, then definitely. If I like the busker's music, I usually give them something.

Hmm. . .thoughtful question. . .the answer is almost always 'no' - but I have busted out the cast twice or three times for musicians, but they were very, very good. . .

If they are good, and they are playing for the hat, then for sure. Especially if they are adding to the ambiance of the street corner, the park or the coffee house.

I'm not opposed to this but, it depends on the venue I suppose. I have occasionally tossed some coins in a street musicians hat from time to time. However, I don't think Paul McCartney would have appreciated it when I attended his concert a few years ago.

I tipped the band members who played at my wedding a year ago. We did that because they were very good and stayed on for a little longer than was arranged. Sometimes a performer on the street or in a restaurant will earn themselves a tip if I have change or a few dollar bills in my pocket.