There are a lot of small ferns which possible to grow with hostas. Such as Polystichum setiferum 'Congestum', Dryopteris erytrosora 'Gracillima' or Dryopt.erytros.'Prolifera'. New fronds of the last 2 are reddish but turn green with age. Athyrium filix-femina 'Congestum' or some of the Polypodiums are also possible to grow. Polypodium vulgare or Polypodium x mantoniae 'Cornubiense'. Your can have a look at some photographs of ferns at my homepage. http://www.farngarten.de/e_index.htm
regards
Athyriana

Also, shade isn't the only type of space in which you can grow ferns. Polystichums and Dryopteris in particular will grow in remarkably dry conditions; some Dryopteris in particular I've had in three-quarter day sun in a dry spot for several years.

The only other outdoor fern besides the painted fern that has a real colour to it is Arachnoides simplicior var. variegata. Hardy to zone 6, though, according to my source, so might not work for you.

Some of the small Woodsias (eg obtusa), however, are extremely cold tolerant (zone 2!) as are the Osmundas, although the latter are very big (but tall, so can fit between hostas :-)). Asplenium (platyneuron and trichomanes) are also small and very hardy. Finally the Adiantum aleuticum/pedatum (maidenhair fern) is very cold-hardy and is so delicate-looking that it would interplant well with hostas without blocking your view of them but tough enough that it would hold its own.

Finally, Polystichum neolobatum and Polystichum rigens are both modestly sized and hardy enough.

You're welcome, Curtis :-)!

I'd suggest A good small fern is the Korean Rock fern, Polystichum tsus-simense. It's readily available from several commercial sources.