This page contains the following solutions.
I found my siblings by googling my maiden name. Two of them had gone onto Facecook and came up in a search I did with Google. Since I have a very rare maiden name, that made it easy.
Locating an Adult Child?
Locating a Half Sibling?
Locating Adopted Relatives
Finding My Dad?
Locating an Ex-husband
Finding a Lost Parent?