I have installed the pCD8544 library for Nokia 5110 from here - http://code.google.com/p/pcd8544/
and the working example therein is the most promising I have come across. It gives a nice display, it handles numerical data, and I have six lines of text.
The only problem is that I cannot re-arrange the pins. It uses pin 4, and I am going to need that for the on-board SD card. On all the other 5110 sketches I have used, a typical one being here - http://blog.stuartlewis.com/2011/02/12/scrolling-text-with-an-arduino-and-nokia-5110-screen/
the pins are defined at the beginning of the sketch. I guess this one defines the pins in the library. This can't be such a good idea. While the other 5110 sketches do not include a library for the LCD, the usual 16x2 LCD does have a library but the pins are still defined in the sketch.
Is it possible to edit the pin definitions in the library?