ScreenGrab.app

(*

ScreenGrab.app
Improved version of the code on
http://applehelpwriter.com/2013/03/12/getting-to-grips-with-applescript/
that replaces the / with . in the screenshot name

*)

set myList to every character of time string of (current date)
set this_item to "."
repeat with i in myList
    if the contents of i is equal to ":" then
        set the contents of i to this_item
    end if
end repeat
do shell script "screencapture -x ~/Desktop/@" & myList & ".png"