I really like the way the caret looks in iOS. Is there a way to make the Mac OS X caret look the same way, system-wide?
It's not possible to change this on a system-wide basis.
The reason is that the cursor is set by the application itself. There's no "system-wide text cursor" apart from the defaults that most applications inherit.
Application developers can change the way the cursor looks in a typical
Some apps have custom graphics that change the I-Beam cursor used for the mouse, such as Terminal.app (in Contents/Resources/ShadowedIBeam.tiff). But none for the actual text cursor.
Basically, you have to hope that the app itself offers a way to change the cursor.