Bugs I might be able to submit patches for:

    
    [LOAD_NONEXISTENT]                                              never mentioned publicly
    [SNAKE_FLOAT]                                                   submitted Jan 30
    http://spelunky.wikia.com/wiki/Bugs#No_Falling_Damage_Bug
    http://spelunky.wikia.com/wiki/Bugs#Uneven_Water_Bug



Unknown how to reproduce:
    [REALLY_PREMATURE_PARACHUTE]                                    submitted Jan 30
    [FREEZE]                                                        mentioned numerous times, but no clear way to reproduce






[LOAD_NONEXISTENT]
    If you hit F3 to load a level, and manually type in a filename that doesn't exist, it will put
    you into a blank level.  If you then hit escape, you get a constant error:

            at position 80: Unknown variable customLevelName


[SNAKE_FLOAT]
    Throwing a pot with a snake in it into a wall makes the snake float up the wall and die when it
    hits the ceiling.  This may only be the level border walls.

                    - recompile the game to make ALL pots produce snakes, and then try to reproduce this

[REALLY_PREMATURE_PARACHUTE]
    The parachute seems to deploy falsely even after a short (two or three tile) drop if you are
    running.


[FREEZE]
    Sometimes the game will freeze, and even if you've only been on a level for 30 seconds, shortly
    after the freeze, the game will say "the ghost is coming!".  Bizzarre.

        SquashMonster has some credible suggestions on how it might be reproduced:
            http://forums.tigsource.com/index.php?topic=4017.msg145521#msg145521