You can also deduct a portion of your computer costs (both hardware and software), office supplies, reference books, possibly even a deduction for home office expenses, depending on how your home is set up and how many hours you work.
Most important advice: Keep a good paper trail and DOCUMENT EVERYTHING. To claim a deduction you must be able to prove that you incurred the expense. Even if you're the type who shoves all your papers into a drawer for your accountant to sort out later, be sure to save every single receipt and invoice!
Someone I know who used to work for Revenue Canada said that more expenses are disallowed because they aren't adequately documented than because there's actually a problem with the item being claimed as an expense.