Supposing I have a program that prints lines with data periodically, how can I turn then info them into graphical plot that updates itself each time new line available?

$ ./prog
10 44
20 66
30 55
40 58
50 59
55 58
60 77
^C

$ ./prog | scrollingplot

Window appears and updates on each line printed:

80|                             
  |                        ----   
  |   ----     ______...__/
  |  /    -----
  | -
40|
-------------------------------
    10  20  30   40   50    60

# Note that ASCII art-style plot is just for example, 
# I want simple X window like in mplayer.

There are enough tools for static data, but I haven't seen ones for updating data (except of ksysguard).