kst is a program for looking at data streams. It can plot:
 
   - x-y plots
   - power spectra
   - histograms
   - equations (including equations of data streams). 
   - data in files which are being updated as data is being logged,
     in which case it can act as a plotter for a chart recorder.
   - much more
 
You can use the mouse to rapidly zoom into interesting parts of the plots.
 
In addition to a complete GUI, kst has a convenient command line interface
for rapid access to plotting data in files. kst can read data from stdin.
It provides a DCOP interface for remote manipulation, and supports several
file formats in use in scientific projects around the world.

WWW: http://kst.kde.org/