The Consumerist has a great writeup of the differences between hard- and soft-credit pulls and how one can negatively affect your credit score.
Also included is a list of companies and other financial institutions and whether they perform a hard- or soft-credit inquiry when you apply for their products (loan, bank account, mortgage, credit card, etc.).
http://consumerist.com/5101305/hard-and-soft-credit-inquiries-and-how-one-hurts-your-credit-score