Disneyland:
There's a permanent Meet Mickey Mouse 'house' in Fantasyland, and the Princess Pavillion where you can meet a princess, both of which are undercover and you can queue for. There is also a semi-permanent (?) area for meeting Duffy and sometimes Minnie in the Square of main street, and another for meeting Winnie the Pooh (and/or friends) at the other end of main street.
We also met Jack Skellington near phantom manor (only Halloween to Christmas apparently)
Have also seen on Twitter that at the moment there's also regular meet and greets on the edge of Adventure land (not far from Pirates ride) for characters like Peter Pan, Wendy, Hook...... Alice and the Mad Hatter, WHite Rabbit, Tweedles, all near the Labyrinth.....
Studios:
A LOAD of characters come out onto the lot near the Stitch show late morning - complete random mix!!
There's two permanent outside meet and greets in Toon Town - I THINK one is always Minnie, and the other is Buzz int he morning and Pluto in the afternoon.
Also once saw Aladdin and Jasmine near the carpets ride for a random meet and greet (Sept '12)
Village:
Cheapest way to eat with the characters is do Cafe Mickey - you don't have to do set meals, you can share pizzas and things, and on average you see around 5 characters (Mickey and Minnie, then others such as Pluto, Eeyore, Goofy, Tigger...)
DLP also have recently started policing the meet a greets in the parks a bit more and creating queues (may long it last!) so it's now very civilized!
Until early November you can also meet characters int he hotels, and you don't need to be staying int he hotels for them either (randomly met the white rabbit in the DLH when we wandered in for a nose and a look around their shop!). Met Jessie and Minnie in our hotel (Cheyenne).
There's also the Decent of the Stairs in the DLH every afternoon where there's about 5 characters who make an appearance.
So as you can see, there's quite a lot!!! Well, I think so. And I'm pretty sure I've missed some!!
C x