Steve Jackson Games has Cardboard Heroes which is a great set of stand up cardboard counters that can be used for D&D. Fiery Dragon made counter sets specifically for D&D that lay flat as did dragonscalecounters which is no longer in business. I think there is another company that makes them for D&D as well but I can't remember the name and I don't have any of their stuff.
There are a number of pdf companies that make sheets of counters you can print out. I found the ones from IDA to be great and stand up well next to minis when you cut them out, fold them into a triangle showing the front and back of the figure then tape the base.
I have the Counter Collection 2 from Fiery Dragon, although I haven't used them...yet.
They are sized for 3.0, not 3.5, so some of them are rectangular. They don't fold and stand in triangles either; they're sized for 1" squares.
They look cool, and I got 400 for $15 several (5?) years ago. I actually asked my FLGS about them and they had some on the shelf...still...just the 'weird' monsters...for full price. So I haven't bought any more.
There's also a company who makes tokens for monsters as well. I forget the name though. They looked cool. AHA! Found it in my favourites: Monster Tiles from Ocho Games
Far and away the best I've found and use regularly are Disposable Heroes. The Fantasy sets (1,2,3,4) are $4 each for a whole bunch of fold-and-stand-up figures.
Best of all, you can build your own sets up from the ones you've bought and print out custom sheets - perfect for that Goblin Army I've been working on.
Almost always. I like the D&D minis and own several of them, but nothing beats cardboard flats for game play. I have almost everything Fiery Dragon has put out and I'm probably getting the Ptolus set soon. It works out much better and saves me from lugging around bulky boxes.
I invested in a copy of Counter Collection Digital. It contains 1800 critter images and I can print out sheets containing the ones I need very easily. It's also cheap and quick to print them onto card and have the sheet laminated. The bonus is that they're also very easy to store and transport.
The Steve Jackson Games Cardboard Heroes page is here.http://www.sjgames.com/heroes/ Scroll all of the way to the bottom of the page for the floor plan packs that include modern figures.