I'm looking to use the sensor to control the motor over the internet without using the ethernet shield
Your question doesn't make a lot of sense. How can you control it via the internet without having some sort of connection to the Internet, either directly or indirectly
I presume your question may be.. Is there any alternative hardware to connect an Arduino to the Internet?
If so, the answer is yes. There are standalone Ethernet (cabled) modules that you can buy. There is also the wifi shield, but I presume you don't want a "shield"
There are some new Wifi to Serial adaptors, but these are in their infancy and you'd need to write all the code for them yourself.