A rat spleen - not more than one - is used in Shrinking Solution (see).
Rat tails are used in hair-raising potion (see).
Re'em blood
The blood of the Re'em, when drunk, gives the drinker immense strength (FB).
runespoor eggs
The eggs of the runespoor are used for making potions which enhance mental ability, though as the runespoor is a protected species, the eggs are traded on the black market (FB).
