I'm not sure how many of you are aware of this. For those of you who are, would you consider marijuana to be an ego softening drug because of the culture and people that it involves? Here's a good article on what ego loss is if you aren't sure of it. Ask Erowid : ID 2758 : What does ego-loss mean in regards to an LSD experiences?
I'd say it probably softens your ego very very lightly. But to be honest I've never gone anywhere near killing my ego on weed I don't really think it's possible. However it is possible on LSD and will more likely happen if you smoke weed near your peak.
i think for a lot of people weed puts thing into great perspective. that should effective in softening the ego.