I will use Bill Graziano, Ken Henderson, and Fernando Guerrero as my examples for this:

• Pick a good topic, cover it thoroughly, and try to provide more than what's expected (Graz, Ken, Fernando)
• Create good slides that are descriptive enough so that notes aren't required (Graz, Ken, Fernando)
• Provide handouts anyway, in case you want to take notes (Graz, Ken)
• Allow for a Q&A session (Ken), or allow attendees to ask as you present (Graz).  Reward questions with food (Graz). :)
• Complement, but don't repeat verbatim, your previously published material (Graz, Ken, Fernando)
• Practice speaking clearly and authoritatively on the topic (Graz, Ken, Fernando)
• DEMONSTRATE, don't just state, what your presentation is about (Graz, Ken, Fernando)
• Be enthusiastic! (Graz, Fernando)

Graz's presentation on Profiler 2005 was the first I went to, and he spoiled me for the rest.  As Mark mentioned, HE ROCKED!!  Enough to be asked to present AGAIN!  I'm pretty sure the 2nd session was even better since he was able to update his presentation with info from the MS developer who wrote Profiler.  He even managed to get the audience to go “WOW!” in unison, when he demonstrated the Perfmon graph embedded in Profiler.  He also gave out candy to people who asked questions, even those that stumped him.

Ken Henderson, of course, is God, and his presentation showed that God is in the details.  Covered EVERYTHING you could possibly absorb in one sitting on Memory Management in SQL Server.  He talked about stuff that was in his book, The Guru's Guide to SQL Server Architecture and Internals, but did not regurgitate it.  He didn't quite finish all the material he had in his presentation, but it was more than enough.  Wish I could've gone to his 2nd presentaion on PSSDiag, but instead I went to...

Fernando's presentation on Hidden Features in SQL Server 2000.  Many of these tricks are relatively well known (DBCC LOG, fn_dblog, DBCC PAGE, sp_OACreate, metadata functions) but he presented them in an enthusiastic manner and demonstrated them very well.  Definitely whetted the appetite to try new things and revisit old stuff with new methods.  He was also the funniest and most entertaining presenter so far (for me at least).  He also ran out of time, actually not able to cover one section of his presentation, but it will be available online within a few days, and he'll have examples available at that time.

So if you're going to PASS next year and any of these guys are speaking, you'd better go to their sessions!  It's like putting money in the bank, at 100% interest.