Supporting members can create birdlists with sightings. From these lists they can generate a World List showing every species they have seen.
Click on World List from the My Birding menu (top menu).
The "My sightings" dropdown is set by default to "Yes". This means that at the bottom of the page you will see your complete World List (all the different species you have sightings for).
Please note that you can filter this list using numerous options: species, family, global conservation status, etc.
You can print or export this list to Excel.