okay, let me get this straight...
1) Belldandy uses mirrors
2) Skuld uses water
3) Urd uses televisions.

is that right?

 That's right.  Urd can also use computer monitors.  To my knowledge,
water does not need to be warm for Skuld to be able to teleport through it,
contrary to the scenario presented by some fanfic writers.  There are no
limitations on the area of the surface they teleport through -- Belldandy has
gone through a car's rearview mirror in the manga, for example.

The Dark Horse/Studio Proteus translation certainly presents Skuld's 
teleportation as being through hot water.  I don't know if this was an error in 
their translation, or if Fujishima contradicted himself later in the manga by 
showing Skuld teleporting through ocean water.  

 And as for other goddesses and demons:
  4) Peorth uses camera lenses (don't know if other kinds of lenses would
     work as well)
  5) Mara uses compact discs (exclusively?)

Ah, but Marller, like any other demon, needs two of the necessary item for 
teleportation to take place.  In other words, she doesn't rely on just one (or 
any) CD to teleport into this world, but she needs two certain CDs (the Gods CD 
and the Demons CD) in order to teleport into this world, acting as catalysts.  

 Anyone know anything about Troubador?

He's been seen teleporting into an area in whirl of cherry blossoms.

-- 
"I will chide no breather in the world but myself,                 _____
 against whom I know most faults." - As You Like It         |_____|_____
                                     Act 3, Scene 2    _____|     |
            Julian Fong: fong_jh@sunset.bph.jhu.edu

Peter L. Ward          falcon@best.com          Kyusaku on IRC #Anime!
Caretaker of the Urd Shrine (http://www.best.com/~falcon/urdhome.htm)

"Okay, *here's* an idea...I've heard the best cure for memory loss
 is...SHOCK TREATMENT!!" - Urd