Have you ever been surfing the net and noticed that you suddenly lost connection? Or that it suddenly became drastically slow? If you don't want to purchase a new router (if you do: buy an N router from either D-link, or Linksys), you can increase your range for free. It is slightly technical, but nothing we can't get through. Ready?
If you have the venerable Linksys WRT54(X) or any other Broadcom based router then I recommend using Tomato firmware, but you can use DD-WRT if you like. Because of its support for a wider variety of routers, I will be using DD-WRT in this article. You can check to see if your router is compatable by checking this list.
Once you have determined if your router is compatible, the next step is to download the firmware. You are going to want to go to the downloads page of DD-WRT.com and download the firmware. But wait! you say...you may have noticed that this isn't exactly the most user-friendly page. How do you know where to click? You are going to want to click on the stable link and then you will scroll down to the latest version of the firmware (dd-wrt.v24 as of this writing). The next step is to determine which version you want. Consult the list (if you haven't already) and determine what chip is in your exact router. Then select your router make, followed by its model number and simply download the correct firmware.

It is important to check the list again, because the process of flashing the firmware varies among the different routers. The page should have the instructions on the far right side. I will go through the process for a Linksys router that I used to have just so you get an idea of how it will work.

Step 1: Reset router to its default settings and then reboot the router
Step 2: Go to the admin page (192.168.1.1 in your address bar of your browser) and go to the firmware page. Browse to your downloaded firmware (it will be a .bin file) and click the upgrade page. Wait for a minute or so and it should reboot on its own. If it doesn't, simply unplug it for 30 seconds and plug it back in again.
Step 3: Confirm it worked by logging into your admin page again.