You'll want to use sayreg to register these

$MPIVerbs       Allows MPI to control verbs/speech
$OldVerbs       Recognises old _(o)say<ch> style verbs
$PuncVerbs   F  Selects a verb based on speech punctuation
$RandomVerbs    Not a filter. Random verb program.
Capitalise      Capitalises initial letter of each word in speech
Elmer        K  A filter that makes you sound vewy vewy siwy.
Halt            Explicit termination of filter search
Jumble       K  A filter that jumbles up your words.
Lisp         K  A simple lisp filter
MixedCase    K  Capital letters? Lowercase? Huh?
Muffle          Sets random characters to a 'blank' character.
Null            Placemarking null filter
PigLatin     K  Self explanatory, I think.
RandWordDup     Duplicates words random(ish)ly
RandomSplit     Randomly but sensibly splits your text.
Replace         Standard Replace filter. Based on Lynx's.
ReverseChar     Reverses speech char-by-char
RoomEcho        Naff room-echo FX. Please write a new one.
Sesame          Open Sesame. A voice-activated locking system.
SpeechCall      Primitive 'filter' interface to ( s -- ) programs.
Stutter      K  Add a stutter to your voice.

K - Written by Kimi@FurryMuck
F - Written by Fre'ta@FurryMuck

Filters not written by me may not be copied without obtaining the author's
permission.