1) There's a literal dungeon in the Tarant sewers, far more extensive than the small portion you've probably already explored with the gold ring fetch quest. It's most easily accessible from an entrance south of the docks, near where the gypsy lives near the edge of the city.

Protip: One of the items you'll find is cursed; and if you aren't running the UAP the curse is permanent. Hopefully you have the patch already installed, because you can't continue to play any pre-patched games afterward.

2a) As you walk between towns, you're likely to stumble upon old caves, ruins, etc. These are probably worth your time to explore. Be sure to get magic items identified before using or selling them. If you're willing to cheat, you can even search for (and download) a full map of the continent, with all location spoilers revealed.

2b) As an alternative, you can just wander outside of cities to provoke random encounters, keeping the good stuff to use or sell and discarding the rest. You don't even need to wander; once you've found a good location (as determined by having an encounter with anyone who drops loot) you can just sleep there for a day at a time, hoping to repeat as often as you have patience (or cargo space) for.

3) Similar to the way Akalabeth's lucky number system works, the combination of your PC's name, race, gender and background generates a unique and repeatable key that determines the contents of all randomly-assigned treasure chests. (Note that not all treasure chests are random.) This means that a determined player can try different names, just to see what the Kite Shaman's magic chest at the crash site offers up. (Capitalization counts as well, so that MacDonald is different from Macdonald, for example.) A good haul can be sold for much gold, allowing you to purchase better armor and weaponry once you get to Tarant.