Other things to look out for
Here are some of the common things you can expect to see in Berlin:
Ampelmann
Meaning "traffic light man", Ampelmann could be found donning his distinctive hat on traffic lights in East Berlin while under the rule of the DDR. Around 10 years ago they starting removing Ampelmann from East Berlin and replacing him with regular western figures, but Berliners protested and they stopped. Now, whenever traffic lights in both East & West Berlin need replacing, they put in Ampelmänner. In the past you would have been able to tell whether you were in the east or west by looking at the figures on the traffic lights but today, for the reasons stated above, it only works around 80% of the time.
There are Ampelmänner just outside my flat, which make me smile every morning when I cross the road to get to the tram stop.
Stolpersteine
Translating to "stumbling blocks", these are small gold plaques which are placed outside places where Jewish people used to live. These little memorials can be found all over Germany (except Munich) and generally contain information such as name, date of birth, where the naz_s sent them and what their fate was. Tragically, this is generally "ermordet" or murdered.
Bears
Being the city's mascot, bears are decorated and can be found in random places everywhere, such as this one near Potsdamer Platz (the financial district):
Pipes
Colourful pipes can be found around any construction site (so most of the city). Because Berlin was built on a swamp, they're there to drain the water out from underneath building sites.
Cobblestone wall markings
There is a continuous double cobblestone line marking where the wall used to be, generally marked with plaques. If you are reading the plaque and it is the correct way up, then you are on the west side.
Markings on every tree
For some reason the government keeps a log of every tree in the city. Take a quick look when you walk past one, it'll be numbered.
Scammers & pickpockets
Sadly, scammers & pickpockets seem to be found wherever there are tourists. One of the most common scams are the people (often children) who walk around with clipboards claiming to be from a deaf/handicapped charity. They try to get you to sign their fake petition, then ask for money. The charity is fake and these people don't even get to keep a cent of what you give to them. Please don't give anything to these people.