cornkid,
No other material is nearly as good a filament as tungsten. The main issue is not mechanical strength, but rather a combination of melting point and rate of vaporization. Carbon filaments have a melting point of over 3500 C, which is certainly quite high (slightly higher than tungsten, even) but the carbon vaporizes relatively quickly, which means that in practice, tungsten filaments cannot be run hotter than 2500. The result is a light that is yellowish and an efficiency of only 7 lumens/watt.
Tungsten on the other hand has a melting point of 3383 C, but more importantly it has a very low rate of vaporization which allows pushing the filament to very, very close to it's ultimate melting point.
Despite a great deal of research, no better incandescent black-body radiator material has been found.
The main variations you will notice are whether or not the lamp is a pure vacuum or is filled with a noble gas (such as krypton or xenon) or with a noble gas together with a trace amount of a halogen (such as bromine or chlorine).
Anyway, back to your question, the main issue of filament life is not how strong the material is, but rather what its rate of vaporization is. The non-halogen lamps will blacken over their life span, while the halogen's will be every bit as bright right up until they blow. This is due to the "halogen cycle" which redeposits vaporized tungsten atoms back onto the filament (cool, huh?). Unfortunately, they do not redeposit the atoms back onto the same spot from which the left, nor is it a random process. The atoms are more likely to be redeposited onto the cooler areas of the filament. This means that the thin spots get thinner and the thick spots get thicker, and pretty soon, a thin spot gets so hot it vaporizes entirely and that's pretty much all she wrote.
Interestingly enough, the incandescent technology is not quite fully mature: research on flourine as the halogen additive indicates that it would not favor the cool spots over the hot, and thus would theoretically enable an almost unlimited life-span (!) (short of dropping and other impacts, of course) Unfortunately, the flourine attacks the filament and lead in wires while the lamp is cold, and at the moment, no way has been found around this problem.
