All of us have experienced spotty wireless connections at some point. Too many times have I wanted to toss my PS3 controller across the room because of those nasty red connection bars while playing Call of Duty. Thankfully, there are a few good ways that you can easily achieve increased signal strength and stability.
NOTE: I strongly recommend you use only one of these solutions at a time, using more than one will put tremendous stress on your router and WILL significantly reduce its lifespan. Use these solutions at your own risk, I am not responsible for any damage you may cause to your router.
Solution 1

If you are not very tech savvy or generally prefer a quick-fix approach, Solution 1 is for you. All you have to do is steal one of your moms aluminum foil pans (the bigger the better), and simply stand it up behind your PC/PS3/360. Thats it, your done! Sounds stupid, but it works. The pan will concentrate the signal around your device, resulting in roughly a 10% boost in signal. If you want to take things further (or if your mom needs her pan back), you may want to adopt solution 2 or 3.
Solution 2

Solution 2 involves creating your own antenna out of paper and aluminum foil. I wrote an article on this a while back, check it out here. You can expect a 12dBi gain with one antenna. To further increase this gain you need to either use more than one antenna, or increase the size of the antenna.
Solution 3
This solution is the most advanced of the three, however it has the potential for the greatest gain in signal strength. First things first, you will need to download and install Tomato Firmware (you will need either 7-zip or WinRAR to unpack the files). Tomato Firmware is replacement firmware for your router (see compatiblity list), featuring an easy to use GUI, bandwidth usage, and many customization options. Once you have installed the firmware, you will need to go to your default gateway (192.168.1.1 for Linksys). If you do not know your default gateway, go to START -> RUN -> type CMD and hit OK. Command Prompt will open, type ipconfig and hit enter. Your default gateway will be in the list of results. Once you have entered your default gateway and logged in to the firmware, go to Advanced -> Wireless. Look for the field “Transmit Power” (value should currently say 42mW or so). This value can be increased up to 251mW, but your router will likely turn into molten plastic. I recommend a 10-20% increase in the value, so about 5-10 mW. Thats it!
If you run into any problems read over the readme.htm file or check out the FAQ’s.
NOTE: The FCC has guidelines with regards to the strength of wireless signals, thus increasing your signal may be breaking them.
Click here for two more methods of increasing your wireless signal!