myairplane.com has all kinds off cool stuff. Plane background checks, and all sectionals online are 2 and 3 on my list, but the #1 is the free approach plates. Good for when you use the free sectional, to find a place a ways away to go. Check if there is an approach for that area, if needed. Then you can go back and buy what you need for the area.
Not that I've ever gone across multiple sectionals yet, but I see it as a cool way to do initial flight planning. And you can see what areas other are talking about without having to shell out $7 or whatever for a chart, or another few $ for a local plate book. I use Jepp plates anyway, but I'm into free resources out there (as I'm sure many starving pilots are