Would you like to use your Pi as a WiFi router? Or maybe have it as a special filtering access point? Setting up a Pi as an access point (AP) is a bit more advanced than using it as a client, but its still only a half hour of typing to configure. If you want to, this tutorial will make it so the Pi broadcasts a WiFi service and then routes internet traffic to an Ethernet cable. Since its all Linux you can go in and update or configure it however you like.
I used the following pages as a guide to create this tutorial, please note many of them will not work completely, but check them out if you are interested!
Currently tested working on Raspbian only
Full article here:
Setting up a Raspberry Pi as a WiFi access point (Adafruit Learning System)
We would not purchase a Raspberry Pi solely for this purpose, since you can probably buy a dedicated router that will act as an wireless access point for less than the price of a Raspberry Pi, power supply, SD Card, and WiFi adapter. But if you already have a Raspberry Pi that is loafing along doing some task that doesn’t make full use of its capabilities, this might be an extra task you could give it, particularly if it happens to be in a spot where WiFi reception is a bit spotty.