
If you ever grow weary of Inconsolata, try monofur. Adding Truetype fonts to Linux is a piece of cake with fontypython. Just install it via Synaptic or apt-get.

convert -page a4 *.png images.pdf
import sys
from subprocess import Popen, PIPE
PAGE_WIDTH = 210.0
PAGE_HEIGHT = 297.0
files = [arg for arg in sys.argv[1:-1]]
output = sys.argv[-1]
tmp = ["a4%s" % f for f in files]
for f,t in zip(files, tmp):
p = Popen(["identify", f], stdout=PIPE)
dim = p.communicate()[0].split()[2]
w,h = [float(d) for d in dim.split('x')]
bw,bh = 0,0
if w/h < PAGE_WIDTH/PAGE_HEIGHT:
nw = PAGE_WIDTH * h / PAGE_HEIGHT
bw = int((nw - w) / 2)
else:
nh = PAGE_HEIGHT * w / PAGE_WIDTH
bh = int((nh - h) / 2)
Popen(["convert", "-border", "%dx%d" % (bw,bh),
"-bordercolor", "white", f, t]).communicate()
Popen(["convert", "-page", "a4"] + tmp + [output]).communicate()
python img2a4pdf.py *.png output.pdf