(See the best response by Super Saiyan X.)
Problem description:

Is there anyway to have text already in an input box, and when you start typing it goes away? It would say something like "Type something here to search".

The only way I can think of is have a label ontop of the input with transparency, and have each keystroke check if your current window is the input or not, and winshow or hide the label based on whether or not the focus is on the input box. However I want something more simple if possible.

If not, is my method very demanding? I don't like calling procs per keystroke.

You could check which control has focus, and when said control had focus, remove the text.

It's the only way I can think of.
Yes, we are thinking along the same lines here.

However I was unaware you could just have pretyped text in a input?
Best response
You can just set the command of the input in the interface editor as '!search pls', I think.
or use winset on the input as command or text param.
In response to Super Saiyan X
In response to NNAAAAHH
NNAAAAHH wrote: command_text

(Note: In BYOND 4.0 this var is deprecated. The command parameter for an Input control can be set to !command which does the same thing. See the skin reference for details.)

So, exactly what I said.
In response to Super Saiyan X
Which is why it was directed at you and not the poster.