You can also get reliable Flightaware tracking by doing this:
File an IFR flight plan (yes, even if you're not IFR qualified or intending to fly an IFR flight) BUT put (exactly like this) VFR/8500 (or your appropriate VFR altitude) into the Altitude field on your on-line flight plan tool, and put VFR ADV into the "remarks" field.
The characters "VFR/" followed by a VFR altitude will ensure that you do, actually, get a VFR flight plan, but it will be tracked and passed on as though it was an IFR flight plan. VFR ADV in the remarks field will be a reminder that you're asking for VFR Advisories. This has an additional benefit; when you launch and contact Center or your local TRACON in the air, they will already have your squawk code waiting for you.
For filing flight plans and online flight planning, I haven't yet found a tool to beat
www.fltplan.com. You can't beat the price, and - although it takes a bit of getting used to - I love the features. For passengers taking their first (or rare) flight on a private plane, the "passenger briefing" printout is an inspired bit of class.
Oh, and I - too - use the SPOT tracking beacon thingy. My wife absolutely loves it, because she can see where I am when I fly long solo cross-countries.
Hope this helps someone!
Kevin