If you want to find out some great benchmarks and best practices for webcasts, check out ON24 2010 Webcasting Report.  The results are from evaluating 10,000 demand generation webcasts from 700 corporate clients.  To peek your intereset here are the key findings: 

  
•  52% of all registrations occur in the ten days before a scheduled webcast, with 15% registering on the day of the webcast.
• Given average registrant-to-attendee conversion ratios, 33% attended during the live webcast, while an additional 25% viewed the archived webcast.
• Webcasting is an effective and popular way to reach audiences year-round, including during holiday and summer months.
• The average viewership per webcast is 38 minutes