Do you come here often?

While not really difficult, this puzzle by Mike Torch was a lot of fun, as it emplys a lot of modern and colorful words.

Main Clues:
Never - "whenhellfreezes"
Sometimes - "onceinabluemoon"
Always - "twentyfourseven"

Just these big clues show how hip this puzzle is. But wait, there's more:
Like a multipurpose tool, perhaps - teninone
Big Apple daily, briefly - nytimes
Excused oneself, with "out" - bofed
Dance, slangily - hoof
Internet music-sharing service - kazaa

I'm really surprised they worked in Kazaa and even a self-conscious self-reference to the times itself. Super coolio.

Things to learn:
Lethe - a river in Hades; the souls of the dead had to drink from it, which made them forget all they had done and suffered when they were alive.
Erte - pronounced R-T, the initials of Romain de Tirtoff, french art deco designer.