If more folks could afford them, big game hunters would absolutely LOVE the Dakota line of cartridges. I have a 330 Dakota, and were it legal there is nothing that walks this earth I wouldn't hesistate to tackle with it. Power of a 375 H&H, flat shooting of a 300 Mag, hits with a 250gr bullet. The dakota stock configuration makes it recoil like a 30-06. Amazing rifle.

As far as other calibers that didn't ever get popular that should have.... for deer hunting of course the 6mm Rem (which has been talked to death already). As well as the 6.5x284 which is starting to gain some following in the benchrest arena. Heck of a good round.

Other one that I'm sort of suprised has almost completey dissppeared is the 6.8 SPEC. Would have made a good round for kids in a Model 7. Not that the .260 isn't, and I love my 7mm-08 which has now really gained a good following.