Like everyone else here, I was too young to have ever used them. In the US, as was posted above, they were on the market from 1965 until November 1983, when they were pulled off the market. Methaqualone, the active ingredient was then put on Schedule 1 in 1984. The main reason for this was due to the extreme abuse potential of methaqualone in addition to the fact that it was a fairly risky drug in terms of safety. OD's were fairly common. Originally, Quaaludes were produced by the William H. Rorer company until about 1981-82 when Lemmon started producing them. Methaqualone was also sold in the US under a bunch of other names including Sopor and Parest.
Methaqualone (with diphenhydramine) was still on the markets in Canada (under the name Mandrax) until the early 90's, although I'm not sure if it was prescribed much. Mandrax is still abused in South Africa where it is smoked from a glass bottle neck. Apparently, methaqualone is still on the market in some European countries and can apparently be obtained in India and China.