Speaking engagements make my top 6 list of best marketing activities. Like writing articles, columns, or books, speaking adds the additional advantage of putting you in the same room with potential clients where you can demonstrate your knowledge and expertise AND develop an emotional bond with your audience. These opportunities have led to immediate work when a potential client in the audience has an immediate problem relating to the same issues raised in the speech. Moreover, if the seminar or speech is sponsored by a respected organization, you receive instant credibility as a result of that association.
Paramjit Mahli of Sun Communications Group recently had an article in Small Firm Business that had some good pointers on how to get started, and what when and where to focus your efforts to land speaking opportunities. It is worth reading.