If you are smart you are using Employee Referral Programs to help find job candidates in a difficult market. You have to keep hiring to find talented people and moving ahead of your competition for when the market turns around.
What makes employee referrals so powerful is that it is that word of mouth marketing that can make a huge difference for companies just as it does for any product that is being marketed. People trust people, more than they trust big corporations.
A challenging economy requires intelligent budgeting and ERPs give you a chance to find ideal candidates without spending a fortune on head hunters and external recruiting solutions. You have to be balanced with online advertising and other intelligent avenues of recruiting, but an effective ERP needs to be huge.
Also they can reach so much farther as a corporation than as a department that gets labeled as annoying. Let's be honest, a person would like to hear from a peer in the department that they would be working with, than a recruiter that has a potential bias just to get you hired.
You have to be careful to make sure that your employees are being used wisely so they are not distracted from their work and that they don't get frustrated. It can backfire and hurt you, them, and the candidates.
It is necessary to use web 2.0 or interactive online marketing IM Chat or RSS feeds to get your candidates talking to your employees. Putting a face to your college candidates and experienced candidates will give them more of a reason to join your company.
A lot of companies use niche sites for individual employees or microsites to help motivate candidates to find out more. This allows for many websites (needing optimization of some kind) to be out there for people to view.
EnticeLabs has a great product called TalentSeekr that allows for you to brand your company, work culture, exciting projects, and job benefits. They also do an amazing job of leveraging sites by using SEM with many publishers they have relationships with all over the web.