My own school's PTA also does a jog-a-thon and every year what we've raised has gone up. This year we raised $54,000, $14,000 over the projected amount.
I did a break down on prizes in another post so I'm just going to link you to that post (it's rather long)
A few things not mentioned there is that we bill this as our ONLY fundraiser. A promise not to nickel and dime the parents for the rest of the year. We're multi track year round and we two jogs, two tracks each. Kindergarten runs smaller laps and does them alone. (20 yards) 1-3 runs in the morning and 4-6th runs in the afternoon. We've offered pizza through school lunches so the parents can come have lunch with their kids. (It works with the free lunches also) This didn't raise any funds since they just paid the hot lunch prices to the school but it did require that the parents RSVP.
The jog/pledge sheets have lines for per lap or flat pledge. We also have out of town mailers for the kids to send out. They have 1 month to collect pledges. On the back of the sheet is the permission form. We close out the jog 2 weeks afterwards. We also have given each child that participates a water bottle the day of the jog and we have in the past given them a ribbon (but the water bottles were donated)
It took me a while to find the prize list (August of last year)
www.ptotoday.com/ubb/ultimatebb.php?ubb=...f=15;t=000686#000002
I really think it is the only way to go! Any-thon is a good fundraiser for the schools in my council that does it. They always earn great money.