Banner ads yield two benefits. First, they may entice users to click on the banner and go to the advertiser's site. Each time this happens is called a "clickthrough", and the number of clickthroughs divided by the number of impressions is called the "clickthrough ratio" or "click rate". This is easy to measure, and provides a direct measurement of a banner's effectiveness.
The second benefit of ad banners is building brand recognition. Whether brand recognition is part of your strategy depends entirely upon your individual situation.

Niche/Industry Specific Sites

These include sites dedicated to a specific audience or industry. Sites like this are all over the Internet. You just have to know where to find them.
These are usually smaller sites dedicated to recruiting in specific fields with diverse audiences.
They will reach a smaller but more qualified audience
You can locate these niche sites using Yahoo and finding industry or occupation links

We all know them. They include Careerbuilder, Monster and HotJobs among many others.
They cover a broad collection of industries and occupations
Most have a keyword searchable database
They may allow for employer profile information (benefits, company location, logos, etc.)
They will reach a very large audience


Resume Databases

You can find potential employees all over the Internet. Many will post their resumes in more than one resume databases available online. Most of the major job sites offer resume database access, as do most of the niche/industry specific sites.
Professional & Trade Associations
Many associations are now on-line which becomes a great source to access members who are looking for new job opportunities. There are several ways to locate these associations.

Email Marketing:

Your Own Database
Recruiters and HR professionals are just starting to realize the benefits of opt-in email marketing to source potential candidates. In the recruiting world, this represents an untapped form of relationship marketing that comes right from your existing resume database. Instead of losing candidates that didn't work for a specific position, email marketing allows you to keep in touch with candidates while keeping your name out there for the future.

Renting Lists
Marketing companies rent lists of email addresses by skill sets, geographic regions, or zip codes. These lists cover a wide range of specialities.

Email Newsletters
Paid recruitment advertising spots in newsletters are available. Distributed to subscribers on a regular basis, email newsletters tend to be cheaper and are filled with non & recruitment information the subscriber has requested.