If you know a location, try looking for a local web site -

My family was originally from Ayrshire, and this site has helped -

http://www.ayrshireroots.com/

I'm sure equivalent sites exits for other areas....

Google a few of your family names with known locations and something may pop up.

...and after you have bugged your family members as stated above, get them to give you any copies of letters/postcards/pictures they have.

Scan them and distribute to other family members with as much information as you can gather about the picture.

I kept telling my dad, "details don't count if they are in the attic and no-one else knows they are there"...