If in the past you had to go through a day's worth amount of work to get ndiswrapper to work then today ubuntu and its derivatives finally came up with an easy solution: b43-fwcutter.
First of, make sure that you actually have a broadcom chip. Use
lspci
to get a list of your hardware and look for a wireless devices. Mine was
03:03.0 Network Controller: Broadcom Corporation BCM4318 [AirForce One 54g] 802.11g Wireless LAN Controller
And now just install
b43-fwcutter from your package manager, follow the wizard, reboot (it doesnt tell you to but it won't activate otherwise) and you are done!