which is rare, but it happened a few minutes ago, I don't know why (it's back now), you can read:
Almost all my Snape/Harry stories -> on
TSS 2,
My Snape/Lucius story -> on
TSS 3,
Some of my older Snape/Harry stories -> on
WtP,
Some of my non NC-17 fics -> on
ff.net (including some of the "Spice Series" stories and one "Gothic Series" story),
Some of my shorter fics -> on this lovely archive called
Slytherin Selection,
My Snape-Harry Gen Fics -> on
Potions and Snitches.
My drabble in French can be read on
HPfanfiction, and
My Hook/Pan series of drabbles can be read on
peterpanslash.
My penname is always Ptyx or ptyx, except on ff.net.
I posted a few stories on LJ, especially some
drabbles and
all the Spice Series stories except the final ones.
So, I believe the only stories that aren't posted elsewhere are the stories in "The Gothic Series" (except for the one that I posted on ff.net) and the three final stories of "The Spice Series".
[ETA: "Perfection" and other flashfics aren't posted anywhere else either. The same happens with "Getting Better", the sequel to "Not So Bad". I'll try to remedy that ASAP.]