Antoine Craske wrote a really good article discussing some interesting concepts around test automation — the value, the wealth, the processes and the culture.
This is an honest and accurate point of view on test automation coming from Piotr Kałuski's vast experience in the field. Hard to disagree!
Note: If you can't access the full article, simply open it in a private tab.
Hui Ching Lim shares an extensive guide to the dos and don'ts of test automation, including several tips on test code and test design. All this is illustrated with examples (as long as you can read C code!).