Holding down the "i" key while clicking on a tile will bring up that item's Get Info Box. This is the equivalent of selecting the item in the Finder and choosing "Get Info" from the Finder's File menu. "i-clicking" on items is handy for increasing memory allocations for applications, checking modification dates, pasting in custom icons, and editing comments.
Printing Items from the Palette:
Holding down the "p" key while clicking on a tile will print that item if the item is a document and can be printed. This is the equivalent of selecting the item in the Finder and choosing "Print" from the Finder's File menu.
Duplicating Items from the Palette:
Holding down the "d" key while clicking on a tile will create a duplicate that item on the desktop. This is the equivalent of selecting the item in the Finder and choosing "Duplicate" from the Finder's File menu.
Revealing Items Attached to the Palette:
Holding down the "r" key while clicking on a tile will "reveal" that item on the desktop. OneClick! reveals an item by opening and displaying the contents of the Finder folder that contains the item and highlighting the item. There is no equivalent Finder menu selection for this.
Accessing the Preferences Dialog Box:
Holding down the shift key while clicking on a tile will access that palette's Preferences dialog box.
Closing the Palette during Launch:
Holding down the Option key while clicking on a palette tile will launch the tile's item, and automatically close the current palette. This is handy if you are opening a palette from a palette, and want the current palette to close, to free memory for the new palette, or if you are finished with a palette and want it to close after launching a palette item. Option-Clicking on a blank tile has no effect.