I really like the Eiosis E2 De-esser. SOS agrees:
 
"In short, with every source I tried, E2 De-esser was orders of magnitude more successful than any other de-esser plug-in I had available to me. There's a comprehensive preset library, but I generally found it easier to set up by ear, a process made easier by the Listen modes and the ability to A/B two sets of settings. Because sibilants are processed separately from the rest of the audio, you can treat them as aggressively as you like without affecting the overall sound of a vocal.
 
All in all, though, I'm hugely impressed with this plug-in. Eiosis have applied fresh thinking to an old problem, and their solution leaves existing de-esser plug-ins in the dust. Renaissance De-esser has had a long and distinguished career, but now that E2 De-esser is installed on my computer, I can't see myself going back. I don't know what Eiosis are planning next in the E2 series, but if it's as good as this, I can't wait to find out." 
                                                                                                                                                           Sam Inglis SOS April 08
 
 

Sonnox Suppressr is my favorite de-esser, closely followed by FabFilter Pro-DS.
 
I have the Eiosis E2 as well and it's nice, but I don't think it's anywhere near the quality that the SOS review gave it (one of the reasons I bought it btw).  Now that Fabrice has joined the Steven Slate crew, he's apparently abandoned the plugin anyway and it's stuck in 32-bit land.  I've tried contacting him numerous times to see if I can sell it, but I've never gotten a reply (apparently, word-of-mouth says I'm stuck with it).

I use envelopes on the s consonants at the same time I pull down the breaths.
The VX64 de-esser is pretty good so I often put that across a track as well and always turn the screw on the CA-2A.
I also put a really deep broadish eq cut on the reverb (usually 6-8Khz) as well to take out the s tail.

A zero-cost solution would be to get someone to punch your teeth out.
With that in mind, you could try different lip positioning on 's' sounds. Tightening the bottom lip can dampen the 's', but be careful not to sound short tongued. Widening the gap between your lips might also work. Maybe pulling the tongue back slightly would help.
Essentially, you are exploring mouth shapes that reduce the sibilance without affecting you tonal quality too much, and then training your muscles to repeat the action. My idea may work for some people and not for others. I only just tried it myself, but with practice it may be a good solution without spending cash on tech and banging your head over an EQ meter.
Of course, tight lips and growling teeth would look odd on a stage, but in a studio, who cares?
 
Anyway, give it a go. Let me know how you get on. Not punching youre teeth out of course.
 
Regards,
 
Lee.

Bristol_Jonesey
I find sibilance is sometimes caused by excess compression. Backing it off a bit can help, in some circumstances

Good advice, Colin. This has caught me out before. I've tried de-essing before the compressor, but sometimes backing it off is the only answer.

Other than that, the Vx-64 works quite well, especially if you use the listen facility, or whatever it's called.

Automation envelopes can also help, as several people have stated.

One of the best de-essers ever is just using one band of a multiband compressor.  This is usually far more flexible than a de-esser.  You can precisely zero in on the offending frequency, you can tweak the threshold and gain reduction ratio, you can tweak the release.  You can also adjust the Q or bandwidth of the sibilance - how many de-essers give you that?
 
Basically, far more tweakable than a de-esser, but will out-perform virtually any purpose built de-esser ever made.
The Sonitus multiband compressor included with Sonar will do a stellar job.

Best De-Esser in my world is...
 
 
SPL De-Esser
http://www.plugin-alliance.com/en/plugins/detail/spl_de-esser.html
 

 
Nomad Factory BT DEESSER DS-2S
 http://www.nomadfactory.com/products/bt_dynamics/index.html

 
 
I have both. I use SPL most because of VST3 Support and I think it sounds the best between the two. Its very close. 
BT DEESSER DS-2S sounds analog and wonderful too.  
 
 
Best Regards
Freddie