Earlier this year, the Commonwealth Court began allowing e-filing through PACFile. The Commonwealth Court is a mid-level appellate court that reviews certain types of cases - most notably for me, it handles appeals from the Unemployment Compensation Board of Review.
This is really a great convenience. You don't need to worry about catching the mail carrier, crossing your fingers on overnight deliveries, or worst-case-scenario: the dreaded run to the courthouse to file it in person. Hopefully we'll get all Pennsylvania courts on this system. Of course, for federal courts we already have PACER. Neither system is perfect - but both surely beat physical delivery.