It's a pretty long list :-) Vinca minor would certainly work, although some would argue it's plenty aggressive as well. IME, it is FAR less agressive than ivy and MUCH easier to remove if it does wander. Other choices could be ajuga (needs some sun to bloom nicely), hardy gingers (Asarum species), lamium (dead nettle), Galium odoratum, Cornus canadensis (bunchberry), wintergreen (Gaultheria procumbens), Euphorbia robbiae, various shade loving hardy geraniums or dwarf Sarcococca. Liriope or dwarf mondo grass is also often used in these conditions but spread tends to be very slow compared to other choices.

With that much ground to cover, you may want to expand your choices to include plants other than common groundcovers. Hostas, ferns, astilbe, epimediums and brunnera are all possibilities but any shade loving perennial or low shrub could work. A few hellebores would be a great addition as well, but make sure they get at least partial sun.

Thanks for the big list, Gardengal!

My overall plan is to put down a metric crapload of mulch in about a 4"-6" layer over the whole area. I can get it for free from the town so it's the least expansive thing to try and hold the ivy back. Also, I figure that it's better for the environment than plastic or landscaping cloth.

After that I'm going to go with some native perennials and some ground covers to try and make an inviting area out of the jungle that is there now. I'll take your list as a starting point for several sessions of Googling images of plants!

I was going to post an addendum to my first response about making sure all the ivy was removed before planting anything else.......guess I should do so now :-)

English ivy is not the easiest plant to eradicate and you will have very little success by just trying to smother it, especially with any type of organic mulch. The ivy will simply growth through it in time. And the roots can remain viable for an extended period, even when top growth has been removed. Manual removal is the most effective method - it just requires a lot of elbow grease but you must remove as much of the root system as you can manage. An alternative is to cut back top growth and paint the exposed stems with RoundUp concentrate. This typically takes a couple of applications for full effectiveness. Just spraying RoundUp or other herbicide on the plant is not very effective as ivy leaves have a waxy surface or cuticle that resists herbicidal penetration. And be prepared to pull ivy seedlings for some time as well.....

I do not recommend attempting to short cut this approach. You will continue to battle the ivy endlessly and have just a giant mess if you attempt to plant before removing or eradicating ALL the ivy.

The point is well taken, GG. I did a bit of it last year with a weed-whacker and it came right back. This time around I'm getting face to face with the evil stuff and going with a more manual approach. It's taking a lot longer and my back may never be the same again, but I'm seeing a lot fewer pop-ups behind me.

Would a layer of cardboard under the mulch help at all or would it just be a waste of time? I'm reluctant to use any kind of synthetic weed killer. Then again, where in the heck am I going to find 1/4 acre worth of cardboard? :)

There's an article on eradicating ivy at http://seattlepi.nwsource.com/nwgardens/212274_lovejoy17.html

They make the point that some people have a poison ivy-like skin reaction to English ivy, so it's a good idea to wear long pants, long sleeves, and gloves. I yanked out a lot of poison ivy last spring--though nowhere near a 1/4 acre!--and got a rash. I was never sure whether it was the ivy or poison ivy.