Working at a Pharmaceutical or Biotech Company
This will be a very different experience from working in an academic lab.  Research projects are carried out by teams, and of course the scientific work is typically very focused on developing drugs.  All the issues related to organized internship programs in academic institutions also apply to those at companies.  At a company, you may have to apply for an internship via a bureaucratic human resources department, and you may only get through to the scientists once you get past HR.  Thus it may be very unclear exactly what you will be doing or who you will be working with until after you apply.  As a result, it may be hard to predict what kind of experience you will have, and different interns may have widely different experiences at the same company.  Larger companies offer internships in research, but also in the business and legal aspects of the pharmaceutical industry.
 
Companies have an ulterior motive in running these internship programs.  They hope to attract the very best interns to come back to the company in the future as employees, perhaps after a few more years of academic training.
 
Listing of organized internship programs at pharmaceutical and biotech companies.
All the big pharmaceutical and biotech companies run summer internship programs for college students.  The following are links to the internship programs at a set of companies that were rated as the very best employers in the industry in a recent poll carried out by Science magazine.  The list starts with the top ranked company and then moves down the ranking.  The deadlines and mechanisms for applying are quite variable - you will have to click through all the links to see the details.
 
Genentech (South San Francisco, CA)
 
Boehringer Ingleheim (Ridgefield, CT)
 
Roche (Palo Alto, CA)
 
Amgen (Thousand Oaks, CA)
 
Genzyme (Cambridge, MA)
 
Johnson & Johnson (New Brunswick, NJ)
 
Eli Lilly and Company (Indianapolis, IN)
 
Novartis (Cambridge, MA; Basel, Switzerland, Horsham, UK)
 
GlaxoSmithKline (Research Triangle Park, NC)
 
Wyeth (Princeton, NJ)
 
Pfizer (six locations in the U.S.)
 
Biogen Idec (Cambridge, MA; San Diego, CA; Research Triangle Park, NC)
 
Merck & Co. (Westpoint, PA; and two NJ locations)
 
Abbott (Abbot Park, IL)