Nullyifying specific avatars parts

my sugestion would be to allow the removal or shrinking to null size of arbitrary parts (ears, arms, whole heads etc) of the avatars body by the user for purpose of replacing it with prim based ones or simply to not have it at all (if someone wanted to have a "crippled" avatar or something similar)

ps: alowing alpha-ing the parts could help but would be a less than ideal solution

It realistically doesn't look like this would happen soon--major changes to the avatar mesh, that is. However, there are going to be significant avatar improvements on the way, including Physical Avatar--a bit more info is here:

http://secondlife.blogs.com/change/2006/06/kicking_off_sec.html#more

In the meantime, yup, you can have an prim with a special "invisiprim" alpha texture and wear it as an attachment to hide body parts. Jacek Antonelli had a really cool "segmented" effect I saw him use yesterday. Related:

/109/95/112223/1.html

Another trick is using a high-priority pose (uploaded animation) to fold parts of your body, e.g., arm tucked inside the torso. I've seen that done too.