I've dealt with it a few times. I had interviewed for a teaching position at a community college, interview went well (interviewed with the vice president). I was told only thing needed was approval by the president, and it it should take a week at max. Two weeks pass by and I hear nothing. Call back and and had trouble getting in contact with the vp (he not in his office according to his secretary). I was finally able to get a direct line to his office and he seemed surprised to hear from me. He said the president has been busy and hasn't made a decision yet, and he would mention to the pres again.
Another 3 weeks pass by, and nothing. So I just said forget it.
Most recent job I interviewed for, I had to go through a thorough background investigation. Once everything was done I was told I would hear from HR and they would let me know if I got the job. Three weeks go by and I hear nothing. Finally I email HR inquiring if I got the position. 5 mins after sending the email I got a call from HR telling me I got the position and they are sending the contract in the mail