The back of Gordons "Introduction to Old Norse" has a limited but very
useful dictionary.

Everything costs money.

My copy of Zoega was republished in 1988, but it still cost me US$100. But
for my work, it's indispensible.
The online version has been a long time in coming, but I see some progress.
I wish them the best. Too bad it's not in a searchable database format
though.

> Moreover, what dictionaries I've found for modern
> Icelandic to and from English have seemed small and limited.

Find dozens of Icelandic/English dictionaries here:
www.malogmenning.is
Everything from children's schoolbooks to college, technical and specialized
professional dictionaries. They have an english translation of the site.

Mine is a two volume set: 'Ensk-Íslensk Orðabók' by Sigurdur Orn Bogason and
'Íslensk-Ensk Orðabók' by Arngrímur Sigurðsson published by Mal og Menning
(Ordabækur Ísafolder) in 1994. It's specifically for use by professionals
and scientists doing business between Iceland and abroad. Almost 2000 pages
of modern Icelandic and English words. Of course, each volume was US$90 but
it is the most complete that I've found. I often use it in combination with
Zoega and Gordon (as long I consider the various vowel mutations and
consonant 'irregularities' between Old Norse and Modern Icelandic).

-Laz