Metal miniatures enhance a playing session, but they're expensive and take quite a bit of time to paint. Prepainted metal miniatures are even more expensive. Even plastic miniatures are not all that cheap, and still need to be painted.
Flat cardboard counters are at the other end of the spectrum. They're very cheap, but they don't give the same feel as something that sticks up from the table. Mark Hill has a fine set of downloadable artwork for flat counters; simply print and glue them on heavy cardboard.
Steve Jackson Games sell something that falls between these two, Cardboard Heroes. Unfortunately, their fantasy miniatures product is out of print. And, although they are much cheaper than metal or plastic miniatures (under 5 cents per figure), they're still not free.
The Fantasy Trip have posted a set of artwork for print-it-yourself cardboard miniatures. They're very nice, but don't have all the figures I'd want. Not yet, anyway. If you're going to use these with the miniatures I've got below, note that they're printed in slightly different scales; print the TFT pages at 360 pixels per inch (180 per inch for their goblins), or print mine at 250 pixels per inch, to convert them.
With the artist's permission, I've modified some of Mark Hill's flat counter artwork into cardboard miniatures. I've also taken some copyright-free artwork and done the same. Feel free to download, print, and use these for your own game sessions, collages, or whatever (just don't go and sell them, please). I've put them up in PDF format, which makes them print at the preferred size, and in PNG format, which is easier for cut and paste.
To turn these into cardboard miniatures, I'd recommend printing them and cutting them into strips containing a front image, back image, and two base tabs. Then bend them into a tent shape, and glue the base tabs onto a cardboard base. For a one-hex figure to fit our modular maps, the base should be about 2 cm square (3/4 inch square). 2-hex figures take a base about 1.5 cm by 4.5 cm (5/8 in by 1 3/4 in). Triangular 3-hex figures take a base in the shape of an isoscles triangle 4.5 cm (1 3/4 in) on a side; I prefer to truncate the corners about 5mm. Larger figures should have a base of the appropriate size.