Ultima IV: Quest of the Avatar

You can hit Z for Ztats to wait indefinitely for a moongate to come back into phase without spending any turns. This is handy if you are poisoned or chased by a monster, or you want to farm Mandrake or Nightshade unmolested.

If you find the mystic armor/arms and have all seven companions, have everyone equip them. Then search again. The arms/armor are there if you have none in your inventory. They sell for large amounts of gold, too.

To power up for the Abyss, Jimmy lock the door behind the secret doors leading to the north part of Lord British's Castle. Descend to Hythloth. Cast exit and enter Hythloth (or descend and cast up.)The power ball on the first level gives +5 stats to everyone and recharges when you exit (2W 2N U and back.) But once everyone's dead, they're kicked back to...Lord British's castle, where you can try this again, for the price of a magic key and a spell (30 gold.)

You can steal from Lord British's treasury as much as you want--just take the stairs up and down nearby. Because there is no penalty for (or once) your honor, justice and honesty hit zero, you might as well take what you can. You can recharge these virtues by overpaying reagent sellers by one gold.