Guard Your References
References are often required to land a job. But you should do your best to guard them. Don't give out references until you're well in to the hiring process. Ideally, you won't give them out until there's an offer on the table that you've accepted.
The reason for this is that recruiters use references to build their contact lists. After all, you've probably done your best to get a senior a member of your company as a reference and these are exactly the contacts that recruiters want. If at all possible, give your references to the hiring manager and not the recruiter. Hiring managers aren't likely to call your references more than once and it's just as effective if not more so to have them call instead of recruiters.
Some recruiters will even go so far as to require references before they'll even work with you. This is ridiculous. Such a policy pretty much guarantees that your references are going to get a lot of calls and that's a sure-fired way to get them to stop being good references.