Agreed with pash. You make it seem like the OP should ask for a raise, get it, then ask for another raise after getting more offers. No employer will look favorably upon asking for two raises in quick succession.
Let me rephrase it as I understand it: ask for a raise. If you get it, then look to get another job where you can get an even higher raise. If you don't get that other job, then stay. If you don't get a raise in the first place, either stay or look for another job.
Leave because you don't like your job, or because you'd really rather being making more money elsewhere doing something else. If you like your job, give your employer a chance to pay you enough to keep you.
I don't think he was saying use the counter offer as a raise, I think he was saying use the first raise to leverage a higher offer from a perspective new employer.
On 50k, ask for raise, now on 65k.
Ask new employer to beat current salary, offer of 80k.
Without the first raise you don't get to leverage a higher salary at the new job for the 30-50k op needs. And good luck getting 30k raise at the same job, that just doesn't happen.