Hi,
Here is some info that might be useful for some highly regarded schools. A threshold (but not necessarily firmly enforced) c.250 is quite popular. As you already know, the TOEFL can be waived in many cirsumstances.
Vanderbilt
"We do not require minimum TOEFL scores, but we prefer candidates whose total score is at least 250 (computer-based test) or 600 (paper-based test), with minimum scores on each section of 25 (CBT) or 60 (PBT)
Official TOEFL results are valid for only two years. If you are applying for Fall 2004 admission and you last took the TOEFL prior to 2002, you must take it again"
Stanford
"Stanford University requires a TOEFL score of 250 (computer-based) or 600 (paper-based) for graduate study in any program."
"Following ETS guidelines, GMAT results prior to January 2000 and TOEFL results prior to January 2003 are not valid for Fall 2005 applications."
Georgetwn
"The minimum required TOEFL score is 600 for the written test and 250 for the computer based test. For the IELTS, we require a minimum score of 7.5 out of 10 on the academic module. We accept only academic module results."
Mich St.
"All international students must submit a TOEFL score to be considered for admission. A minimum score of 600 (paper version) or 250 (computer version) is required. If you have graduated from a U.S. or English speaking university, you may submit a request with your application to waive the TOEFL requirement. (Proof of the mode/method of instruction is required for consideration)."
Carnegie
"What is the average TOEFL?
A minimum score of 600 PBT/250 CBT is required for international students entering the MBA program."
Washington Univ (Olin)
"What is the minimum TOEFL score you accept?
The minimum score we accept is 243 on the computer-based version or 590 on the paper-based version."
Hjort