What you mean is a portal where you can easily provision turnkey VM's? (Preconfigured Virtual machines)
I know you could download images from for example: turnkeylinux.org or bitnami.com/stack.
Otherwise you could setup a puppet or chef environment, who can provision such virtual machines. Only you have to build it by yourself.
Some disadvantage of turnkey images, is that they are out of date. Better would it be to create a new machine automatically and configure with Puppit or Chef the functionality of this particular machine.
Yes, turnkey VMs that are being offered by the Nutanix comunity (CentOS DNS, DHCP, NTP servers, etc) and external providers (f5, cisco, citrix, etc), that way they could be up to date. You could easily go download one from bitnami or turkeylinux but it would be pretty neat if you could just order one from the Prism UI.
Amazon does have both options at the moment. But this does suffer from deprecated VMs and containers being offered.
You could set an environment with a CM but given that 4.7 doesn't offer elasticity as right now (hopefully they do get around it on 5.x) is easier just to clone a golden VM using Prism. On Hyper-v and vmware environments there are workarounds for this too.