The only place I am aware of is the Features & Proposals section of the official wiki.
The challenge we have in general with feature requests is that a good place to ask assumes that there is some chance of developers reading and implementing it (or at least replying to the request).
However, developers get asked for features a lot (personal emails, on IRC, mailing lists, on social networks even!) — so chances are, you are not even the first person to ask for it.
The ratio of people asking questions to those who can implement them is so high that its difficult to usefully manage requests.
Especially since Blender is general purpose 3D software, there are so many things you might want to do, depending on your project.
Taking this into account, here are some suggestions:
If nothing turns up,
- Ask on the bf-functionality board
- Ask on rightclickselect.com
(community run web site, currently in development)
- Find the developer who works on this are and mail them personally, see Module Owners
- You could look into funding the feature, Either by hiring a developer directly or contact the blender institute (via the blender network)
If you can put your money where your mouth is, then BlenderNetwork is where you will find people willing and able to commit time and knowledge for addon development or additions to the core. If you go this route then making changes available to the public has the advantage that anyone can help bug-fix and improve such development efforts. Maintaining your own build might not be an option, without paying for long-term support.
Else you are left to the mercy of fellow blender heads to see the merit of your feature request, to the extent that they are willing to commit their own time to making it happen or help you some part of the way. A curated feature request daughter site of SE would be interesting, but don't underestimate the power of BlenderArtists, BlenderStorm, and Twitter hashtags
Requests on the wiki
It's a good idea to hunt through the current collection of feature requests, you might find yours is already on this list. If it's close enough to what you want then consider updating it or make a new one (but explain why the existing one is different).
Presentation and content of feature request
First impressions matter. The presentation and content of the proposal / feature request are going to be deal breakers. A good proposal has several key properties, and includes:
- An unambiguous definition of the request,
- A well written use-case for the request,
- A list of well-reasoned arguments identifying why current methods are not sufficient
- Isn't too ambitious as to require a platoon of coders to implement.
I don't know how important it is to have prominent donating users undersign the proposal, if ideas are good/useful and simple to implement the chances of success does increase.
I'm not sure how many of these requests are actually acknowledged, but I know that BlenderStorm is one place to request them.
Also, if you can get featured on BlenderNation for some reason (i.e. creating a funny short animation requesting the feature), that's another way.
If you would like to know what features are being added, check out BlenderGuru's "Is it in Blender Yet" list, or chat with the developers on Blenders Developer IRC channel (go to channel #blendercoders).
There's a new 3rd party site designed for this purpose:
The site itself seems to be still very much in development, but it's likely the most active place for feature requests at this time.