Exhibit 24 DIRECTORS AND/OR OFFICERS OF PENTON MEDIA, INC. ANNUAL REPORT ON FORM 10-K POWER OF ATTORNEY KNOW ALL MEN BY THERE PRESENTS, that each of the undersigned directors and officers of Penton Media, Inc., a Delaware corporation, hereby constitutes and appoints David B. Nussbaum and Preston L. Vice, and each of them, as the true and lawful attorney-in-fact or attorneys-in-fact, with full power of substitution and revocation, for each of the undersigned and in the name, place and stead of each of the undersigned, to sign on behalf of each of the undersigned an Annual Report on Form 10-K for the fiscal year ended December 31, 2005 pursuant to Section 13 of the Securities and Exchange Act of 1934 and to sign any and all amendments to such Annual Report, and to file the same, with all exhibits thereto, and other documents in connection therewith, including, without limitation, a Form 12b-25, with the Securities and Exchange Commission, granting to said attorney-in-fact or attorneys-in-fact, and each of them, full power and authority to do so and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as the undersigned might or could do in person, hereby ratifying and confirming all that said attorney-in-fact or attorneys-in-fact or any of them or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof. This Power of Attorney may be executed in multiple counterparts, each of which shall be deemed an original with respect to the person executing it. Executed as of this 21st day of March 2006. /s/ DAVID B. NUSSBAUM /s/ HARLAN A. LEVY - --------------------- ------------------ David B. Nussbaum Harlan A. Levy Chief Executive Officer and Director Director (Principal Executive Officer) /s/ PRESTON L. VICE /s/ PERRY A. SOOK - ------------------- ----------------- Preston L. Vice Perry A. Sook Chief Financial Officer, Secretary Director (Principal Financial and Accounting Officer) /s/ ROYCE YUDKOFF /s/ DAVID POWERS - ----------------- -------------------- Royce Yudkoff David Powers Chairman Director /s/ VINCENT D. KELLY /s/ ADRIAN KINGSHOTT - -------------------- -------------------- Vincent D. Kelly Adrian Kingshott Director Director /s/ PENI A. GARBER - ------------------ Peni A. Garber Director