You see folks, Im Dming a campaign where the yugoloths are up to their own nasty business, and the planes are showing signs of a major loth scheme (I wont go into details, and neither will the rest of the party if they know whats good for them *shakes fist at self, gets confused, and reaims it at the screen*) and the party voted to try and ask Vecna whats going on.
Why Vecna? Well, we dont know whats going on, no one we know knows whats going on. And there are signs of major cover ups whenever we get close. So, if its so closly guarded, it must be a secret. Therefore falling under Vecna's jurisdiction. So, find Vecna!
The thing is, when I tried to look him up in the MotP (cause I saw the home areas of most of the gods I knew of there) I couldnt find Vecna! Except on page 88, and there he's only mentioned in passing.
Is this some sick twist that the location of the god of secrets has to be secret? Even to the DM?
Note: I did hear about the Die Vecna, Die! adventure, but I don't know the outcome that well. Is Vecna dead? If so, where was he before that? Because well have to say this is before that then...
Oh Vecna, where have you gone?
Didn't the Sinkers retake Cavitius according to PS3E? Some sort of a deal with the Dustmen and the undead, IIRC...
I think so, yes.
That's an imortant thing to mention: the Doomguard ruled Cavitius for a time (though they did not build it). Vecna took it from them.
He's more powerful than ever now. He can probably take it from them again.
Makes you wonder if they were the ones that built the other three Citadels.
Architecture in general doesn't seem to go well with the faction dogma, but according to FM and ITC, the Doomguard of old were actual guardians of "doom", not its promoters (I can't remember whether they opposed the process actively, or just guarded it from unwanted interference). Either way, they could've been the ones that built them, but it's more interesting to theoretize about alternative builder(s), isn't it.
On the other hand - never underestimate the *diety* aspect of Vecna when you're trying to get in contact with him. For as yet undisclosed reasons - I needed to contact the OneEyed Freak in Shemmie's storyhour game.
Doing this was relatively simple - it involved sacrificing a chicken. Literally. Clueless went out to the Outlands and improvised a prayer/sacrifice requesting Vecna's attention. I baited it with enough curious information that I was sure he'd react. And voila - turn around and there's a servitor sent to represent him that I could ask my questions of.
Dieties have long ears, you don't have to go visiting them where you live. And being Vecna - and evil and all - it's probably best NOT to drop in unannounced.
Dieties have long ears
That's why I usually refer to them as Powers. Safer that way. 
Well, he is all skin-and-bones, so maybe that's who overweight people pray to when they want to lose a few pounds. Necromantic weight-reduction could be a lucrative side business for any Power. 
Well on the other hand it could be...No no! My lord Vecna I I didn't mean it like...aaarrrrggh!
Gerzel, im compelled to ask....
How long have you been waiting for an oppertunity to use that joke?
The Prayer to Lose Weight? How about...
The Prayer to Induce Erection.
The Prayer to Maintain an Erection.
The Prayer to Silence Barking Dogs.
The Prayer to Silence Car Alarms.
The Prayer to Remove Mildew Stains.
The Prayer to Stop Smoking:
Our most Holy Father,
Take from me the choice You have given.
Assume control of my will and habits.
Wrest from me power over my own behavior.
May it be Your decision how I act.
May it be by Your hands, my every failing.
Then if I still smoke, may I accept that my smoking is
Your will.
Amen.
The Prayer to Prevent Hair Loss:
God of ultimate stewardship,
Shepherd of thine flock,
As You would succor the least of Your charges,
As You would rescue the most lost of Your lambs,
Restore to me the full measure of my glory.
Preserve in me the remainder of my youth.
All of Creation is Yours to provide.
All of Creation is Yours to withhold.
God of limitless bounty,
Consider my suffering.
Amen.
Note: All of the above quotes are from C. Palahniuk's Survivor.
Dieties have long ears
That's why I usually refer to them as Powers. Safer that way.
Sorry, couldn't resist using that in my sig. Too funny. Double entendre and everything. 
Hope you don't mind. I'm still picturing a rabbit-eared Greater God without a hand or eye, running breathlessly on a treadmill.
Ok ok - so I can't *SPELL*!! *ducks her head and hides*
That's practically the same pun.
Vecna is undead, but he's a living god. He was a demigod before Die, Vecna, Die!; now he's a lesser god.
Until recently, Vecna lived in Citadel Cavitius, a skull-shaped fortress-city (also a prison, but not Vecna's prison; it was the prison he kept his enemies) in the Quasielemental Plane of Ash, just over the far border with the Negative Energy Plane. Then he was swallowed by the Demiplane of Dread; he finally escaped in Die, Vecna, Die!.
According to Deities & Demigds Vecna now lives in the Material Plane somewhere (the Sea of Dust in the World of Greyhawk campaign might be appropriate), but I think he's shortly going to want to take his old place in the Plane of Ash back... that is, if he's able to take it back. There are stories that some other entity far older than Vecna may have taken control of Cavitius in Vecna's absence.