Digital Ocean is one place to run Tribblix in the cloud.
On Digital Ocean, you will have to upload a custom image. Don't worry, the images have already been created, but you will have to upload them yourself. (There doesn't appear to be a way to share custom images.)
In the left hand pane on the console, select Images, and then the Custom Images tab. Then click the "Import via URL" button (it may appear as if it's greyed out, but it is clickable).
The currently valid URLs for images are, for vanilla Tribblix and OmniTribblix respectively:
Upon clicking Next, you'll get a screen to enter an image name, a distribution (you'll have to choose Unknown), and a region for where you want to upload the image to. Then upload.
It will take a little while, but after a few minutes the image will be available. Then, under the "More" dropdown to the right of the image name, you can Start a droplet. You can then select the normal droplet attributes such as droplet size, and an ssh key that will allow you to ssh in directly as root.
As of the m28 release, you can add an additional volume. (This requires the vioscsi driver, which is why it wasn't available in prior releases.)
You may find that a reboot doesn't work - the guest becomes inaccessible. A power cycle from the control panel ought to fix that. This is being tracked as ilumos issue 14526.
There were some older URLs for images:
Those older images currently have the normal jack and root users with the same passwords as the live image. You'll need to ssh in as jack the first time (the key-based root login won't work initially), su to root, and
svcadm restart metadatawhich will resize the root pool and enable the root ssh key-based login.
Remember to change the root and jack passwords.