For my birthday, I was given an arduino uno. What should i do with it (project suggestions)
Well, how much are you looking to spend, because an arduino on its own is kind of useless, you need to buy some electronic parts to attach to it. If you don't have any cash, but you have old stuff lying around you might be able to salvage some parts from there. The older the electronics the better because generally speaking older electronics used bigger components that are easier to de-solder. As for project ideas I don't know what you would find fun and/or useful, but here are a couple that I'm planning on building when I get the time.
1.) In the office we have a wall of monitors that display various information about our servers that everyone forgets to turn off in the evening, so I'm going to use an arduino with an LDR and an IR LED to turn them off when it goes dark at night.
2.) I was also thinking of building a simple weather reporting console, that I would fill with old dials and gauges, and have them controlled by the arduino. No you could go two ways with this one a.) feed in the data from a weather website via serial or ethernet (which I will probably do since I live in apartment) or b.) build a bunch of sensors and put them outside. If you went with A you could easily adapt it to display anything that you could get from the internet from stock prices to the the state of the traffic depending on what gauges/displays you put on there.
3.) I'm putting this one last because it's the furtherest off, but I have wondered how hard it would be to build a police speed radar detector that could be hooked up to an in car computer.
As speedfox said a Uno by itself is pretty much useless except for controlling the LED that comes on pin 13.
How well versed are you in C++ programming? That will determine where you want to start. You can do simple stuff that you might have laying round the house with push buttons and leds or maybe a servo from a busted r/c car. I built a temperature logger for my bedroom in my apartment.
For ideas I suggest checking out the following websites:
Go here, the possibilities are endless http://hackaday.com/