SQL to find visible users (option bit set)
 

SELECT * from vb_user where....

the option bit for visibility is set. (options & 512)==512

Not sure how to ask for bitwise operator in query...

Or maybe there is an easier way to get this info?

Please and thank you.

SELECT username, joindate, options FROM `vb_user` WHERE ( options & 0x0100 ) ORDER BY joindate DESC LIMIT 1

Bingo. Thank me.

Finds most recent member who is not invisible.

Is there any reason why you've used a hex as opposed to a number when checking the bit? I've not seen it done this way before hence I'm curious if there's any advantage :)