Hey, all! I'm looking to start GMing again. I haven't played a PnP RPG in years- almost a decade, probably. But I wanted to get my little sister and friend's kids into the game. Instead of doing it old school, I'd like to use my computer to make and print maps, tokens, char sheets, etc.

Is there an on-line list of resources that are free (or at least cheap) that I can download and use? Especially maps.

Thanks for the help!

You could try map tools. It is free but I find it comes with a bit of a learning curve. There are also token tools and some other useful stuff there. For character sheets, you can use Chummer as it will print character sheets as well as being a damn fine character creation and management tool. You can find a link for it in the Community Projects section here.
There are also books like the 2 Sprawl Sites PDFs from Catalyst that have a bunch of SR related maps in them. If you can dig up an old copy of the original sprawl sites book, it was basically just maps and some descriptions for the first half. If you check Google Maps, there are a number of fine Seattle maps with Shadowrun places on them. Just make sure to use the keyword Shadowrun when searching.
You can also try using sites like Autodesk's HomeStyler for interior maps. Again a bit of a learning curve but it is free.

Chummer is SR4A. NSCG you can find around on the net, it's a SR3 generator that's pretty good. No idea where in the SR3 lifecycle is stopped being maintained though, so it might be missing some stuff from later books.

I think Stahlseele has a link in his sig?

Whoops. Missed the SR3 tag. So yeah, Chummer is out but the other advice on maps and such still works.

Because they work across versions: Methods maps

If you speak French : my Shadowrun resources (and a character sheet in English).

The Cartographer's Guild is also a great resource for maps of all sorts and sizes, good for online games.

The NSRCG isn't complete. Otaku stuff and Sprits ain't in.
BUT it incorporated the latest errata of SR3 stuff at least.

Thanks for the great help. Will put it to good use!

Does anyone know of an online resource where I can get some idea for runs? I'm not very good at coming up with good runs/storylines. My campaign is set in early 2050s, if it matters.

The best resource on that is your local Half Price Books, or Used Book Store. I just found $60 worth of Adventure modules for $20 at my local Half Price Books.

I have most, if not all of the Shadowrun modules. I was wanting to space some of them out for some "home brewed" runs.

Mr.Johnsons Blackbook had a sort of random run table.