Here's a pretty useful piece of info for those of you who worry, "I don't have a serial port in my Laptop/Desktop". Yeah, hardly any new Laptop/Desktop comes with a Serial port. They have been replaced by USB ports.
Most hobby electronics projects involving PC interfacing uses RS-232 serial communication. And also many legacy devices can be connected only to the serial port. USB protocols are complex compared to RS-232.
Our mini-project is about controlling a remote vehicle using a computer. We lacked a serial port in our systems, so we searched to find a good USB-Serial converter. Actually this USB-Serial converters have been in the market since long & many are there.
Here's the one we used, the CP2102 chip manufactured by the Silabs. We bought it from the Extreme electronics website which is by the way a very useful site to start with AVR microcontrollers. Here's the link of the product. http://store.extremeelectronics.co.in/USB-to-UART-Bridge-CP2102-Based.html.
The cost involved is Rs. 400 + shipping charges. But the product is worth it. Because it's so compact when compared to other alternatives. Its actually a USB-UART bridge. ie, we dont have a db connector on it. If you require that go for an FTDI USB-Serial converter cable. In addition to the emulation of a Virtual Communication Port(VCP), CP2102 does a RS-232 to TTL level conversion also where as in most of the other USB-Serial converters the output is in RS-232 voltage level. Implies you need to use a level converter IC to interface with circuits working in TTL Logic.
Device driver for CP2102 for all platforms can be downloaded from the Silabs website. Fortunately Linux users needn't do this since the driver module is already there in your system waiting to get loaded...:-)