Cartridge names do not always make sense. If you factor in names that aren't really the caliber they represent, and cartridges that are named after persons other than the one who actually invented, they make sense less than half the time. In the case of the 30-06 Springfield, it is named so because it is a .30 caliber bullet, in a rifle built by Springfield Armory in 1906. It was basically an improvement of the 30-03 cartridge, with several modernizations in the design.
The .30-06 Springfield cartridge (pronounced “thirty-ought-six” or "thirty-oh-six") or 7.62 x 63 mm in metric notation, was introduced to the United States Army in 1906 (hence “06”) and standardized, used until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy and .30 US Army (also called .30-40 Krag). The .30-06 remained the US Army's main cartridge for nearly 50 years before it was finally replaced by the 7.62 x 51 mm (7.62mm NATO, commercial .308 Winchester).
Stolen from wikipedia:
http://en.wikipedia.org/wiki/30-06
also: In the case of the 30-30, it was so named because it's a .30 caliber bullet, loaded with 30 grains of smokeless powder.
Naming
Although the original name is .30 WCF, the -30 in the designation was added to the name by Marlin, who did not want to put the name of rival Winchester on their rifles when they were chambered for the cartridge soon after its introduction[3]. The -30 stands for the standard load of 30 grains (1.9 g) of early smokeless powder, which was on par with IMR/DuPont's 4064. Over time Marlin's variation on the name stuck, though ".30 WCF" is also used.
again stolen from wikipedia:
http://en.wikipedia.org/wiki/.30-30_Winchester
(I didn't know that about the 30-30, that's why I looked it up.) Some cartridges exist only because one was already in existence, and someone improved it with a different bullet type or powder load, to be able to use it in a different kind of rifle, and yanked recognition away from the original cartridge.
The power of the 30-30 peters out after about 200 yards. (Perhaps more with some modern improvements.) Remember, this cartridge is so old, most hunters had neither the talent, the optics, nor the inclination to take shots beyond 200 yards anyway, so it was perfectly fine. There are probably old-timers who can shoot their lever guns further than that, from horseback, but I don't know any of them. It wasn't until they invented the jacketed spitzer bullet, that could handle bigger shell casings and higher velocities without breaking up in the barrel, that anyone thought it was necessary to issue such a rifle to the regular rank and file. (Model 1903-A3 Enfield rifles, with WWI technology, in the hands of good shooters, have taken shots beyond 1000 yards.)
I know guys who hunt elk with a .243. I know guys who hunt mule deer with a .223. My dad killed three with a M-1 .30 Carbine. (A short pistol cartridge.) Doesn't mean I am going to try it. I don't know that I am either that lucky OR that good.