The conventional wisdom I have heard is that job applicants should offer a range of salaries that they would accept when asked during the initial stages of negotiations. For example, an applicant might say that she would accept a salary in the range of $45 to 55,000. Part of the theory behind this is that if you give just a single number then that will be taken to be the minimum you will accept. If it is low then you might be stuck with it; if too high then you might put off the employer.
Now there is some evidence that applicants would be better off suggesting fairly high figures initially, providing that they do it in a way that does not put off the employer. See Extreme numbers influence initial salary offers.
This advice could have some interesting consequences. Some people shy away from applying for jobs for which no information is supplied about salary. This could actually be to the advantage of the applicant, however. In the absence of any declaration on the part of the employer when the compensation bargaining stage arrives the applicant could suggest a high anchor figure to open negotiation.