The other one...US Postal Service.
The speed isn't great and there isn't much tracking, but First Class International Package is a popular shipping option for the customers on my store. To Canada most packages are under $3.00. Overseas, usually between $6.00 and $9.00. The prices are calculated by the ounce.
If you want faster service and better tracking, don't forget the USPS Priority Mail Small Flat Rate Box. It's a bit larger than a video cassette, you can fit a lot of electronics in it. Shipping anywhere is about $13.
Once you need to send anything much over a pound, USPS starts getting expensive again. But most small electronics are pretty light.
I use the downloadable USPS shipping application and print out my own First Class International Package labels+customs info, then take them down to the post office near lunchtime and pay for them. You might have to train the employees a little bit, they don't see a lot of this. The important thing to get across is that you haven't yet paid for the postage.
For in-States Priority shipping I pay and print online, then drop at the post office. For in-States First Class shipping I print out an address label and take it down to the post office to weigh and ship on the Automated Postal Center machine after hours.
If you're not in the USA, there are analogs for other countries' postal services. China, especially, has really really cheap outbound shipping for small packages.