i'm sure this has all been done before but:

perl -e '
@m=(_,"|")x345;{my@a;!$v{$_}&$_>0&$_<346?push@a,$_:0for($p-1)%23?$p-1:
+0,
$p%23?$p+1:0,$p+23,$p-23;$p=pop@v,redo if!@a;(($r=$a[@a*rand])-$p)**2>
+1?
$m[$r>$p?2*$p-2:2*$r-2]=$":($m[$r>$p?2*$p-1:$r*2-1]=_);push@v,$p;$v{$p
+}=
$p=$r;keys%v<345&&redo}print$l?"":"\ec"."_"x47,$l++%46?"":"$/|",$_ for
+@m
' | perl -e '
$|=print"\ec",@m=map{s#\ec##;split//}<>;{$v{$p=$r||50}=1;my@a;!$v{$_}&
+$_
>0&$_<767?push@a,$_:1for$m[$p-2]eq _?$p-2:0,$m[$p]eq _?$p+2:0,$m[$p-1]
+ne
_?$p+48:0,$m[$p-49]ne _?$p-48:0;select$q,$q,$q,.1;printf"\e[%d;%dH",1+
+$p
/48,$p%48;$p>765?exit:1;$r=!@a?pop@v:$a[@a*rand];push@v,$p if@a;redo}
';
[download]

I also have it as 1 6 line "sig", which isn't posted as by my own obscure rules a sig has to be < 4 lines.
this can be seen here
along with my other collection of sigs etc - apologies for corporate p1mpage, but hey....
al

2003-04-27 edit ybiC: <code> tags, un-HTML-encodify of code content (view source for original HTML-encoded code)