Go to Maxim's website
www.maxim-ic.com and look up their MAX6950, MAX6951, MAX6952,...MAX6959 (ten part numbers). These are LED display drivers you can interface on I2C and SPI serial interfaces taking as little as two pins on one of the VIAs on the SBC. Some of them have built-in fonts too, so you don't have to have the processor look up which segments to light up for various numbers and letters.
If you don't mind my saying so though, that's really the expensive way to go about the display job, in assembly time, power consumed, size, and dollars. You can get the intelligent character LCD modules with parallel interface for about $5 on the surplus market from places like Timeline Inc.
http://www.timeline-inc.com/lcd.html , and interface them with as few as six VIA lines (which can be shared with other things too). Timeline has a 40-column, 2-line LCD for $7. Virtually all these LCDs interface the same way regardless of brand because they're all using the same controller ICs. Let me know if you need any help getting it going. I've done it many times.
Garth
engr@drecomm.com