I think it would make sense, since most toads in real life have poison glands, and the poison they carry can potentially be lethal.
I searched a bit and found that poison had been discussed already in these threads:
viewtopic.php?f=5&t=9806&p=106901&
and
viewtopic.php?f=5&t=9753&
However, i have a more specific suggestion. Make it so that toads can be boiled in a cauldron together with an empty jar to procure a jar of poison. For example:
3x



3 Toads, 1 Empty Jar. Boil it in a cauldron and get 1 Jar of poison
Or it could include Toadstool(s) as well, since they are poisonous. This would make the poison a bit harder to obtain. Example recipe:
3x




3 Toads, 2 Toadstools, 1 Empty Jar. Boil it in a cauldron and get 1 Jar of poison
The poison could be used for coating arrows and weapons, poisoning a hated enemy's food/water supply or just drinking it to commit suicide

Thoughts?