This is a table I've kind of maintained off and on for the last decade. It used to have much older technologies, but in the name of readability I'm limiting it to stuff that I actually use, or am likely to use in the near future. The main source I use is List of device bit rates at Wikipedia. Good to show you your choke-points, and also for perspective: 802.11g seems very slow these days ... but if you connect to the world through an ADSL line ... you really don't need a faster WAP unless you're doing a lot of local file transfer.

I hope to update this as appropriate, and fill in the "Practical Speed" column as I can. Note that to do that, I need a source that can max out the technology, and usually that would have to be something further down the table (and thus faster). Those are harder to come by as you move down.

Speeds are in kilobytes or Megabytes per second, using - when I can figure out which is which - the 1000 base not the 1024 base - not because of a strong preference on my part, but because that's what Wikipedia's article favours. DSL and the like prefer to list themselves as Megabits per second (a hang-over from the age of dial-up modems and the baud and marketing's desire to have a larger number) but I'll convert to bytes. Bits are small "b," Bytes are large "B." (See Wikipedia on Binary prefix for a detailed discussion of 1000 vs. 1024.)

Technology Theoretical Speed Practical Speed
Teksavvy DSL6 750/100 kB/s 638/86 kB/s
ADSL 1024/128 kB/s
ADSL2 1536/180 kB/s
802.11g 6.75 MB/s
Fast Ethernet (100BASE-TX) 11.6 MB/s 11.8 MB/s
802.11n Varies, 37.5 MB/s max 7.8-8.8 MB/s
USB Hi-Speed (USB 2.0) 60 MB/s peak 13-25 MB/s
Ultra DMA ATA 100 100 MB/s
Gigabit Ethernet (1000BASE-T) 125 MB/s
Ultra DMA ATA 133 133 MB/s
Serial ATA (SATA-150) 150 MB/s
Serial ATA (SATA rev2) 300 MB/s
USB Super Speed (USB 3.0) 625 MB/s peak 97-112 MB/s
802.11ac 850 MB/s max
USB 3.1 1250 MB/s
Thunderbolt 1250 MB/s x 2