Super Metroid glitches were quite interesting at times too.
On the calc side, I remember the following (there's also a calc game glitches/walkthroughs/secrets section on Omni) from my games
-Metroid II: Expansion Set - Skipping Lower Staria and Boss 2 in Easy mode by going through Lower Inferno lava rooms without Varia Suit. It was also possible to stop lava from rising during the escape sequence in Easy mode by reaching the lava rising room (the exiting it on the other side) before you die, but it was very hard.
-Illusiat 3 experience stacking glitch - when an enemy gave more than 1 level-up worth of experience. And the final boss glitch that causes the battle (and game) to end earlier than supposed under certain circumstances.
-Zelda DLQ skipping switch exploit - Error in map design allowing you to skip a small portion of the 2nd dungeon.
-Illusiat 11 missing Legend Weapon battle terrain - For the optional battle against Legend Weapon in Chapter 5, there's no assigned battle terrain sprite. If you recently re-installed the game and had previously saved progress in Chapter 5, an error would occur if entering that battle. Otherwise, the terrain of the previous battle would be used.