If you hold down certain letters or punctuation on the keyboard, a pop-up appears containing other options. You can hold down the currency symbol to get other currencies. One of the more hard-to-find options is holding the zero key to get the degree symbol.
Two of the most useful shortcuts are found by holding down the comma key or the period key. These display, respectively, the apostrophe and quotation mark symbols. Experiment with the other keys to see what else you can find!