From No Limit Hold 'Em: Theory and Practice by David Sklansky and Ed Miller.
Concept No. 23: It's ok to limp in, planning to fold to a raise. It's sometimes ok even when you think a raise is likely.
This piece of advice is meant for limit players, who are used to automatically calling a raise after they limp in. I certainly agree with this advice; the only thing possibly controversial is that some would argue that you should never limp in, you should always open with a raise. I think limping is fine, though, and I do it often.
Sklansky and Miller give a good, simple example to support their stronger claim that limp-folding is "sometimes ok even when you think a raise is likely." Basically, the example says that if you think your limp for $2 will return $6 on average when nobody raises, then even if there is a 60% chance someone will make a raise and you fold, it's still profitable to limp. EV= (.6)*(-$2) + (.4)*($4) = $0.40. Although this ignores the possibility that raising could be even more profitable than limping, it proves their point that limping can be better than just folding even if you are likely going to fold anyway.