What determines the list of "Recommended Items" in the Auction House?

This is based on personal experience, but so far I've determined:

• A slot is chosen, based on the item levels in each of your equipped slots. The slot with the lowest "Required Level" item in it is usually chosen for the recommendation
• The recommendation list is then sorted by item level, and then by either DPS, Armor, or the primary stat of the hero (for rings/amulets), depending on the slot

I say "usually chosen" because I've seen some odd behavior when a 2-handed weapon is equipped. In some situations, it will pick the 2-handed weapon over other slots with items that have lower levels. Others have reported corner cases where different items are chosen, but I've not been able to nail down why this occurs or how to predict it.

The "hero" in this case is whoever you have currently selected in the character selection menu prior to clicking the auction house button.

There's no accounting for cost or other affixes as far as I can tell. There's also no accounting for the amount of gold you have, as it will often suggest things that cost far, far more than the amount of gold you have.

You also can't sort the recommendation list, even though the "Buyout" column seems like it responds to being clicked on.

I find it somewhat useful to look at this list just to determine where my lowest required level item is so that I can target a search to replace the item in that slot, but otherwise it is pretty useless.

As of right now, the recommendations also seem to take into account what item mods you have on your other items, presumably on the theory that those are the items you prefer. For instance, my monk will see recommendations of items with lightning resistance (which is the one I use for One with Everything), all resistance, life on hit, dex, and vit, since those are stats that I have on many of my items. Not all of the recommended items will have all of those mods, but they do seem to all have most of them.