There are many homes with assumable loans. Many loans made by Wells-Fargo last year for example. You still have to qualify though, and with today's interest rates it is doubtful if you would find it worth while to assume a loan.
Generally, your best bet is to focus on finding the right house for you, then by all means check with your agent if the loan is assumable at an advantageous rate.
Bernard Gibbons, Realtor, e-PRO Certified Internet Specialist
J. Rockcliff Realtors, 15 Railroad Avenue, Danville, CA 94526
Phone (925) 997-1585