I bet there's stuff sitting around that you need to mail. I don't just mean "find a stamp and stick that envelope in the postbox" – though you will take care of that too today – but "find a box and pack it properly and write a note to go with it and look up the address and label the box and seal it up to take it to have it shipped" mailing.
Are there gifts to send? Incorrect purchases to return? Stuff you might as well mail because you never seem to remember it when you see that person face-to-face?
Get it all packed up and ready to go. Put it by the door and take care of it tomorrow when you're out & about.
– some packing/shipping stores are open on weekends
– you can buy stamps lots of places these days
– the postal service has a lot of information on the web about rates, postal codes, customs and other shipping rules
– some enlightened employers have a shipping department that will also handle personal shipping & just charge you the postage