Ebay is a unique place to buy and sell coins.  The market can oft be different, as well as drive the market of regular (non-internet) Coin Shops/Dealers.  Here are some of the trends I observed in the coin market on ebay in 2007:

>Three cent silvers are mainly being collected as a type coin.  Even hard to find dates in problem free upper grades aren't doing that well.  A good time to buy these for sure.

>Peace Dollars are very weak overall, often bringing much less than trends.  I find many of the coin types, such as Indian Head Cents, or Morgan Dollars oft don't do well on ebay due to the large amount of material available at any one time.  Search for any given common date morgan and you come up with hundreds of choices.  This is in stark contrast to Seated and Bust coins.

>Barber mateiral is cooling down.  I've seen even problem free Barber Halves in Very Fine going for less than 70 dollars.  I think a lot of the time the really nice Barber material gets lost in the sea of AG to VG common date stuff clogging the Barber categories. 

>Low Mintage Seated Anything is HOT.  A lot of these coins go well over trends even when the piece has some damage.  The only thing keeping these coins from going even higher is the sheer difficulty of putting together any Seated set (except for Twenty Cent Pieces).

>Bust Halves are SUPER HOT.  This seems to be the biggest upswing coin of 2007.  All dates, all grades.  I think the later date (1827-1836) halves in AU have gotten a bit to high.  These coins are just not that rare.  But problem free earlier Bust Halves are doing extremely well.  The earlier draped bust 1801-1807 coins are going over double trends when even anywhere close to problem free, and those are certainly worth it.

>Lincoln Cents have been going up, and that should continue. 

>Better Date Mercury Dimes have been trading hands for well over trends, especially when they are problem free and original.  Expect to pay one grade up on these when they are nice.  The ever slow to catch on Coin Prices is finally catching up in this area.

>Toned coins, on Morgans or other coins are very hot.  Even common date coins, when rainbow toned, can often sell for moon money. 

>I can't believe the prices some Civil War Tokens have been going for.  Only a few years ago these coins were going for exponentially less than they are today.  Conder tokens, comparitively, have been going resonably cheap (they need their own category, and the market will be there!).  And Love Tokens have been holding steady in 2007.

This guide is in no way comphrensive.  It's just my observations of what I've seen various coins trading for on ebay in 2007.