Used for uploading palettes dynamically. SMW uses this in the lightning/Magikoopa/Big Boo Boss palette effects. $0682 holds the amount of bytes to transfer, $0683 holds the color number (stored to SNES register $2121), and the bytes afterwards hold the actual color values transferred to the CGRAM. Further, this table may be indexed by $0681 to add more color destinations; it's terminated by a #$00. The format is the same as before, just at the new location.
This table doesn't actually have to end at $0694, but SMW never goes beyond this. As such, the area after this address is listed as "empty".