I did this often in previous versions of the Mathematica notebook front end. I would have a cell with lots of raw data, e.g. a very long list. The list might go on for pages. I would set the cell to have a fixed cell height using the options inspector. I could then drag a little box on the bottom of the cell bracket to show only a small fraction, say, the top three and half lines of the input. (I would cut it off in the middle of a line, showing the top half of the characters in the line, in order to make it clear that only a portion was visible.)
I can no longer find this option in Mathematica 8 (Mac OS X). Does anyone know if it may be lurking somewhere else?