Babar,

I've read you used 4094's, and that's what i used too in a project, a few years ago. I had to drive 100 LEDs independently for a factoryplace (manual print assembly). There where racks with 10x10 component places. I used a 8031 for each rack with some extra hardware. on the "display" side I used for the "row"-drive a HEF 4017 followed by npn transistors (use transistors or darlingtons dependent on the total current needed). These drive the common cathodes of the LEDs. The 8031 has control over the reset and clock lines of the 4017.
For the columns I used 2 4094's (8 bit shiftregisters with internal latches) wich togheter are capable of driving 16 columns (in my project only used 10 columns). The outputs of the 4094's are followed by HEF 4050 buffers (which have to drive a single LED at a time each)and a current limiting resistor. Using this system you can upgrade to more columns by using more 4094's. Multiplex frequency is only determined by the clock for the 4017 and the stringlength to the 4094's.
The problem with the LED-brightness? I used ONE ULN2003 between the 8051 ports and the 4017/4094's as a "level shifter". With this technique it is possible to power the 4017,4094's and 4050's at a voltage of 15 volt instead of 5 volt. This enhances the brightness of the LEDs.
The software? I used a timer interupt routine to clock the 4017 and write the "row string" (from RAM) to the 4094's. In my case I used internal RAM for "display memory" but if the messages are long or the display itself is long, you can use external memory, of course.
If you want to know more details, please e-mail me :)

Henk v/d Broek