So a few times per day this guy, and similar guys, come through my street selling 2nd hand stuff from their carts. To let people know they're there, they yell something like "Yehhhhhhh". It sounds really weird.
Besides these, we have accordionists walking the street, stopping on every corner to give their concert and wait for people to throw money out of the windows. Men that sell bread (they carry a huge stack on their head), gypsy women that sell flowers, people that collect water tanks to get them refilled for you... and I'm sure I'll be seeing more of these professions soon... (and recording and uploading them of course ;-)).
More on Istanbul daily life at my blog: BasBasBas.com