Forum OpenACS Q&A: Response to need regexp help: remove spaces and "&"

Assuming you are running nsd8x, you don't even need regular expressions. Using [string map] is easier on the brain, and should execute faster too:
% set text "Bob & Jean O'Connor Jones"
Bob & Jean OConnor Jones
% string map [list " & " and " " _ ' ""] [string tolower $text]
bobandjean_oconnor_jones