The Frequency Analyzer kicks ass. Not as much functionality on it as a moog, but I get a lot of use out of it. Listen for it at the end of this song:
http://download.yousendit.com/F6E5CA44561234EF
It has a lot more uses than that, but since it (and the moog) are both sine wave ring mods, they have a much cleaner sound than other ring mods, and you can get chimey, metallic, and bell like stuff. You can make them sound more vintage if you put a fuzz before them.
Oh, and whoever was asking about crybabies- don't get one, they suck tone like mad. I've never noticed any pedal I've ever owned sucking tone, but a crybaby definitely does.
Also, whoever was talking about true bypass- you don't want everything true bypass, because you can still have a signal loss from all that wiring. You want atleast one buffer in your signal chain too.