Aeroplan, ANA and Continental are very useful for searching *A award inventory. All are free and show generally what is available for *A partners from the various airlines. If you are searching for "local" metal on any of those it might not be available for partners (e.g. CO awards seats that show up on co.com might not be available for US redemption) but overall work pretty well.

For SkyTeam the Delta site is pretty miserable to work with though I understand that there are ways to make it behave; I just do not know what they are. There are a number of other (mostly) SkyTeam partners that are searchable here.

• Aegean Airlines (Business & Economy Class)
• Aeroflot (Business & Economy Class)
• Air China (Business & Economy Class)
• China Southern Airlines (First, Business & Economy Class)
• Czech Airlines (Business & Economy Class)
• Japan Airlnes (First Class)
• Shanghai Airlines (First, Business & Economy Class)
• Tarom (Business & Economy Class)
• Vietnam Airlnes (Business & Economy Class)

The above is a site I operate. I also have an "alert me" feature there that allows you to specify the route, date and fare class and it checks a couple times each day and sends an email if it sees the inventory. I don't have all the buckets listed out yet (hobbies often are overlooked ) but if you know the bucket to be looking in you can add it there. Pretty much limited to the same award buckets as the list (same data source) but it can also be useful for CO B/M-Up fares that book into ZE which is very similar to Z.

For OW awards I believe that the CX and QF sites are the most comprehensive.