I was recently the guest speaker at the local historical society and the topic of the day was making queries on the internet.
There are several different sites dedicated to posting your questions.
one place to find lists are cyndilists
the rootsweb mailing lists.
on the genforum there are several ways to make your listing.
1. you can post it to the state where your ancestor lived.
2. then you can post to the local county or city where your ancestor lived.
3. then you can post to the surname.
when using roots web mailing lists
there are also lists to cover the state,county and surnames.
then there are lists to cover census look ups, city directory look ups etc.
when making your inquiry PLEASE don't post any information about a LIVING person. don't put your snail mail address or phone numbers.
we live in a world of identify theft.
when making inquries PLEASE be specific.
I am searching for ancestor name marriage record in this state in this county during this time frame with this wife.
example: i am looking for the marriage record of john smith in the state of virginia in the county of princess anne between 1800-1812 with wife jane.
you can list his parents, or say that you'd like to find his parents, or you can use his kids to find more info about him .
never post more than 3 generations of information. it's just not needed.
NEVER email someone or post someone YOUR ENTIRE FAMILY TREE. it's not something they need to know.
never post information on people that are living.
do not post social security numbers even if the person is dead.