I'll CAD the schematic later, but my technique will give you
12 LEDs with 4 PIC I/O and 3 resistors.  Z denotes I/O set to
input.

The scheme demands that only one LED be on at one time.  However,
with a little slight of micro, you can easily make more than one
appear on at once.

I worked out a formula for muxing more LEDs by adding more I/O,
but didn't write it down. Argghh!

Heres the truth table for 12:

ABCD  LED ON
----  ------
0000    none
1111  none
zzzz  none
01zz   1
10zz   2
0z1z   3
1z0z   4
z01z   5
z10z   6
0zz1   7
1zz0   8
zz01   9
zz10  10
z0z1  11
z1z0  12

Craig