
Although amigurumi can be either knitted or crocheted, I think crocheted amigurumi is more popular since it is easier to master, and results in a more firm and detailed structure.
Amigurumi are usually worked in parts and then joined by sewing, except for some designs which have no arms or legs. These are worked as one piece. The extremities are sometimes stuffed with plastic pellets to make them more life-like, while the rest of the body is stuffed with fiber stuffing. The creativity and uniqueness will show in the colors, details and embellishments added to the project.

There are plenty of crochet amigurumi designs now available. For free amigurumi patterns go to Crochet Pattern Central.
These are some amigurumis in my to-do list:

Paddy O'possum
Amineko, cat
Lastly for the sake of posting, some of my designs that may be considered as amigurumi:

Fruit keychains
Yin yang ball keychain