Visas can be obtained on arrival at most entry points into Laos.
At the more out of the way entry points you will have to wait some time while immigration takes quite some time to issue a visa.
You will need the following documentation:
Passport
Passport sized photograph
Visa fee of $US 30
Entry points are;
Wattay International Airport.
Louang Prabang International Airport.
Friendship Bridge
Houayxay (Lao) - Xiengkhong (Thai)
Thakhek (Lao) - Nakhonphanom (Thai)
Savannakhet (Lao) - Mukdahan (Thai)
Vangtao (Lao) - Xongmek (Thai)
Namphao (Lao) - Cautreo (Vietnam)
Densavanh (Lao) - Laobao (Vietnam)
Naphao (Lao) - Chalo (Vietnam)
Boten (Lao) - Bohane (China)
Namkane (Lao) - Namekane (Vietnam)
Namsoue (Lao) - Nameo (Vietnam)
Parksane (Lao) - Beungkane (Thai)
Foreigners cannot cross at any other entry points.
Laos visa information
Laos embassies
Laos Foreign Affairs