Well, the easiest way would be to hook up the PS3 via your spare component connection, and then just hook up the Wii via SVideo. Since the Wii only does 640x480 anyways you won't be sacrificing too much video quality.
Many A/V receivers have component switching capabilities, so if you're not familiar with all the options on your model then check that out too. If it does, then you should be able to plug Wii/Ps3 into the receiver via component, and then run 1 component out of the receiver to the TV.
If your receiver doesn't have component input/outputs, and you definitely want to use component for both PS3/Wii, then you're only other option is to pick up an external component switch box. I don't know of any models off hand, but I'm sure someone else can recommend a unit for you.
Lucky kids, my brother and I used to have to share an SNES, and there was NO WAY we'd ever have gotten permission to hook up a second console
. I guess it must be nice to have parents from the Nintendo generation instead of the Atari one..
EDIT: I'm assuming this is an older Toshiba and it doesn't have any HDMI/DVI/VGA connectors?