Well, it's June 2017 and I'm REALLY REALLY late to this. It's 10 years since the original post and 2 years since the most recent.
So, I'm here only because I was reminiscing about a project of this sort I completed in 1980. Google landed me here.
That design required a four-digit hex display, another 4-digit hex display, and a 2-digit hex display.
The standard BCD-to-7-segment decoder chip of that era only handled BCD values from 0 to 9.
I needed full hex, including A b C d E F. The decoder chip for that cost $10 ... or around $40 in today's money.
Too much for me, a recent grad working his first job.
So I did this with a 74154 decoder (takes a 4-bit value and turns on just one of the 16 available outputs) ...
... and a big, hand-wired diode matrix (with 77 diodes IIRC), wired to take the 1-of-16 active outputs from the 74154 and translate it to the appropriate seven segment outputs.
Signal diodes in those days were cheap ... around a buck for a package of 20 from Radio Shack. And the 74LS154 was cheap, too.
If I had back then a ROM programmer I could have used a UV erasable ROM and programmed it for the purpose. I think the common 2 K x 8 ROMs of that era cost around $5, making for a nice, single-chip solution.