Went on a business trip to Long Island mid week this week on the US Air Shuttle. We had an "on time" departure (1Pm was the set time) - meaning that we left the gate like two minutes before the scheduled time, Taxied out to a taxi way, parked next to another jet, and the engines were then shut down. The pilot then announced there had been a ground stop at LGA. We ended up sitting there for 1 1/2 hours! I would have preferred an extra time in the terminal to grab a meal. To make matters worse the 2PM flight was pushed from the gate "on-time" just after we found out that we would be waiting on the tarmac for at least another half hour! The next day my co-worker sat on the tarmac at LGA for 3 hours due to a ground stop at IAD because of the severe weather in the DC area last night. They did not even get beverage service during the delay, since they were forced to taxi around the airport because of the back-up in flights. My gripe is that if I had been informed before boarding that there would be a delay on the tarmac (I had checked in at the ticket counter), I would have gotten lunch and brought it on board with me. I had 20 minutes at the gate before boarding call.