An ASL Wikipedia project is not (yet?) incorporated into main Wikipedia, because it uses SVG rather than plain text, but as soon as the Unicode Consortium adopts
Allocation Count Name UTC Status
1D800..1DAAF 672 Sutton SignWriting 2012-Nov-08
it will be possible to write in many (all?) sign languages of the world in plain text. It is likely that Sutton signwriting is universal ("It has been stable since 2008, having been formalized after 34 years of development.")
The general population can be interested in 1D8C6 SIGNWRITING HAND-FIST MIDDLE UP; the equally interesting facepalm gesture, however, will be composite, probably using 1D90B SIGNWRITING STRIKE SINGLE; I won't attempt to construct it after one brief reading of the document.
A few more curious characters:
1DA0D-10A10 SIGNWRITING DREAMY EYEBROWS
1DA20 SIGNWRITING EYELASHES FLUTTERING
1DA33 SIGNWRITING NOSE WRINKLES
1DA34 SIGNWRITING NOSE WIGGLES
1DA5A SIGNWRITING TONGUE LICKING LIPS
1DA5E SIGNWRITING TONGUE MOVES AGAINST CHEEK
1DA6C SIGNWRITING EXCITEMENT
The comments I've received demonstrate that misconceptions about sign languages are very widespread. Most people, it seems, tend to believe that sign languages are nothing more than shortcuts for fingerspelling.
The fact that sign languages may have - and do have - their own grammar is a surprise for them.