Free TI-84+ Emulator
Pearson TestNav provides a web-accessible TI-84 emulator.
Step 1: Go to http://minnesota.pearsonaccessnext.com/stand-alone-calculators/ Links to an external site.
Step 2: Click "Grades 8 and 11 graphing calculators"
Step 3: Click "Start"
Step 4: Click "Start" (again)
Step 5: Click the calculator icon at the top of the page.