Spreadsheets for Scientific Computing?

redcliffe asks: "Sometimes it's much easier to create a spreadsheet to do some mathematical calculations for physics than to create a whole new program to do the calculations. It's also handy to be able to easily change one figure and have all your other calculations update. But there a certain types of calculations that normal spreadsheet apps like KSpread don't seem to handle well. Anyone know of a spreadsheet or something similiar designed for scientific computing? I've seen GNU Octave, but that's almost like writing a whole program, and without a GUI it's hard to learn quickly."