I don't know if this has been done yet but, I would like to see community supported mastering chains on a download site. By that I mean users being able to post their saved pro channel FX chains on a dedicated Cakewalk B-board for others to try. Often a lot of time is taken up with tweeking individual settings on the dynamics and FX to get the sound that is required. The presets supplied are limited so how about releasing monthly, a few  presets for users and supporting community posting as well. It would provide an 'easy' way of competing with a certain competitors product and give more choices to the users.

While I am not against sharing Effects Chains, I think you will end up disappointed in the results of trying different people's effects chains.  Every song is different.  Even the same song, mixed by different people is different and needs different treatment for mastering.
 
Your best bet is to learn the mastering process and use your ears to get the sound you want, because you will have to do this anyway with someone else's preset.
 
Another alternative is to use LANDR.

Perhaps maybe ask people to describe their chains and why they use specific sequences of plugins, their philosophies, and how they get to the results they usually aspire to.
 
One of the things I feel I do well is compete in the loudness wars. One of my own secrets for that is to roll of extreme low and high-end in a Linear-phase EQ, compress to taste with a modeled compressor, then use TWO limiters in succession to bring the overall level up without pumping. Although I don't use Sonar for Mastering unless I pre-master stems, my chain consists (typically) of EQ to fix issues => Multiband compression to fix issues => modeled compression for glue => EQ for taste => light dynamic EQ to enhance transient attack before limiting, then, Multiband limiter => Multiband Limiter/dithering.
 
I use extensive metering as well. I use Nugen Audio's Monofilter to tighten the low-end to the center if needed, but it's metering can show where the low end might be out of phase. I also use Wavelab's Loudness metering as well as Nugen Audio's Master Check to validate how the mix will sound on iTunes radio, for example.
 
I never go outside the box anymore. I think those Mastering chains are a bit overrated these days.

mastering is based on decisions.
 
presets are based on guesses.

Sonar does have Mastering Template FX Chains (since the Hopkinton update).
 
https://www.cakewalk.com/Documentation?product=SONAR&language=3&help=NewFeatures.23.html

I used to love presets too. It was a great way to quickly get something to sound different. Trouble was, different didn't usually meet the needs of the moment. It was useful, however, to see what settings were changed and then try to understand how each setting affected the sound.
 
Regards,
Dan

Too be more specific, I think it would be an advantage to have an online choice of chains or even cheat sheet settings for the dynamics and FX, for those occasions when time is of the essence or you are recreating a particular sound. How much simpler and easier would it be if your trying to recreate a 60s vocal style and Cakewalk or a user has already created the perfect chain for the application. Perhaps you need a current  style of vocal / instrument /mix and don't have the time to fiddle with settings to achieve it. Personally I've created a song or instrumental from scratch in as little as an hour and then spent innumerable hours trying to get the compression, E.Q. and FX right. I agree with dwardzala et al that it's personal taste, but it's a lot easier when you have presets or listed settings (for dials and knobs on plugins) as a starting point. I say this as someone who used to create DX100 presets in my youth. Myself and my  fellow DX users would share their presets via their dedicated sheets or in magazines. The project templates are a starting point but a dedicated site / BB for sharing chains and presets would benefit everyone.

I think what you mention in the post above is different than your original post.  Mastering (mentioned in your original post) is a very specific activity (and not really what you are talking about above.)   However, effects chains presets which create a style or vibe could be useful and we actually have a pretty significant number of them contributed by Anderton.  But a user library with more of them wouldn't be a bad thing.
 
Since you brought up Synth presets - those are things I would find far more useful as synth programming is (to me anyway) a very technical and relatively non creative exercise.