i am thinking of making a transistor shield, but im ont sure if it already exsists, or if its dumb...
Shields are like questions, there are no (at least very few) dumb ones. It totally depends on what you want to do with it. Describe what you want to do and maybe someone knows of a shield that does that. If not, go ahead and make it.
i myself am going to use it to power high amperage leds, but it would have many uses... it would have screw terminals, and 0.1" female headers for both in and out, and 0.1" male headers for connecting to arduino... also, it will have female pins so you can connect other shields...
Shields are like questions, there are no (at least very few) dumb ones.
Three words.
But I agree, transistor shields would be useful IMO. They've probably been done on a hobbyist scale, but I have never seen one commercially.
AC Power Shield
as in its dangerous, or as in it already exsists?
As in it's more dangerous than the danger shield :).
There's no harm in recreating things that already exist :). Sometimes reinventing a wheel can be fun.