Type The Type Tool creates text for placement on images. It is bound to the Y key. It allows you to choose the font, the leading, the spacing, the alignment, and the type style. Rumour has it that version 4 will offer these amenities. Command temporarily activates the lasso.
Option temporarily activates the eyedropper.
It can be modified via the select menu, it can be an operator in a boolean selection, it can be used as a constraint mask, etc. A weird functionality that the type tool has is that command -dragging with it will drop that bounded region of a floater. For more information, please see the masks section of the page. Because the selection acts like a constraint on all other tools and filters, you can take different coloured brushes and paint over text for an interesting effect. You can try the gradient tool onto selected text for gradiated text.