Here is how to turn Raspberry PI with Linksys WUSB100 v2.0 adapter and Raspbian into wireless access point. This might be handy for conference rooms where you have wired connection, but wireless signal is too low. Just quick setup on Raspberry, plugin the cable and you have wireless available.

Install required packages

apt-get install firmware-ralink wireless-tools hostapd bridge-utils

Modify /etc/network/interfaces to add bridge interface

auto lo br0

iface lo inet loopback
iface eth0 inet manual

allow-hotplug wlan0
iface wlan0 inet manual

iface br0 inet dhcp
bridge_ports eth0 wlan0

Once network configuration is modified reboot Raspberry PI.

Create /etc/hostapd/hostapd.conf file to define access point configuration

interface=wlan0
driver=nl80211
bridge=br0
country_code=PL
ieee80211d=1
ssid=raspb3rry-wifi
hw_mode=g
channel=6
wme_enabled=0
macaddr_acl=0
auth_algs=1
wpa=2
wpa_passphrase=raspberry123
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

Add configuration information to /etc/default/hostapd

That will make hostapd daemon to start automatically each time Raspberry PI will bootup.

DAEMON_CONF="/etc/hostapd/hostapd.conf"