We know folks from a good many places. While this may just be a list of applications that use jclouds, the good people behind these applications are valuable members of our community.

Abiquo Uses jclouds for OpsCode Chef integration, for AWS integration, and internally to communicate the UI with the Abiquo API
Adobe Uses jclouds to provision EC2 and vCloud infrastructure under their Enterprise PaaS
Amdatu Storage Exposes multi-cloud blob services to Amdatu tenants
Apache ACE Uses jclouds to launch nodes in Amazon EC2
Apache Karaf Cellar Uses jclouds to provide a node discovery mechanism, it currently uses a BlobStore whiteboard/blackboard pattern and it will switch to a compute based solution soon
Apache Camel Enables interaction with cloud provider key-value engines (blobstores) and compute services
Apache Whirr Uses jclouds to as a substrate for cloud cluster provisioning
Blow! Uses jclouds for cluster deployments in the cloud
Chef integration jclouds bootstraps nodes based on chef run-lists
CloudBees Orchestrates provisioning workflows over jclouds provider APIs using Scala
ClouDesire Uses jclouds to provide multi-cloud deployments of its applications
Cloudsoft Uses jclouds to underpin Apache Brooklyn
Cloudstore Uses jclouds to enable non-technical users to run web apps on EC2, Rackspace and others
CloudSwitch Uses jclouds to extend application management to Terremark
CloudTran Uses jclouds and Apache Whirr to deploy and test CloudTran applications on GoGrid and RackSpace
Dasein Cloud Uses jclouds for Rackspace, GoGrid, Azure, and Terremark integration
ElasticInbox Uses jclouds to store email messages on blobstores such as AWS S3 and Apache Whirr to deploy ElasticInbox and Cassandra instances
enStratus Through Dasein-jclouds integration, enStratus manages more compute and blobstore providers
EnterpriseDB Uses jclouds in its DBaaS public and private cloud offering, Postgres Plus Cloud Database
fluidOperations eCloudManager Uses jclouds for monitoring and provisioning cloud services from different vendors like AWS and vCloud
Funambol Uses BlobStore to help synchronize content across multiple cloud providers or locally to disk
Fuse Fabric Uses jclouds for creating/provisioning the agents that run in the cloud
GigaSpaces Cloudify Uses jclouds to provision compute resources from multiple cloud providers for the GigaSpaces Cloudify PaaS
GoGrid Uses jclouds to test development versions of their cloud platform
Gravitant cloudMatrix Uses jclouds to access enterprise clouds such as Terremark and Savvis
I N F I N I S P A N Uses jclouds to persist the state of the grid to blobstores such as Amazon S3
Jenkins/Hudson jclouds launches slaves for Jenkins on any supported cloud
Karaf Integration Provides managed service factories and command line support for easily creating and managing blobstore and compute as OSGi services
MaestroDev Uses jclouds to start and provision servers on public/private clouds as part of the source code to production workflow, and for building, testing or deployment
Maginatics Uses jclouds to integrate with a variety of object stores
Manageacloud Uses jclouds to orchestrate servers in different clouds
Mastodon C Uses jclouds via Pallet in order to provision carbon-neutral Hadoop services
Mesosphere Uses jclouds to provision Mesosphere clusters on both Google Compute Engine and Amazon EC2
Meteorite Hosting Enables users to spawn BI environments across a range of cloud providers in a hassle-free way
NeoLoad Uses jclouds to manage load generators in the cloud
Nimble Uses jclouds OSGi integration to deploy Nimble OSGi container instances into public clouds including Amazon EC2, GoGrid and Rackspace
Nimble Servers Uses jclouds to provision servers on public clouds in response to user demand
Ning Atlas Uses jclouds to provision machines, databases, and loadbalancers that compose environments
Omixon Uses BlobStore for big data transfer and made Apache Whirr to provision Hadoop
Pallet Uses jclouds clojure to manage node counts and provision instances
Paremus Service Fabric Uses jclouds OSGi integration to deploy Paremus Service Fabric across public clouds including Amazon EC2, GoGrid and Rackspace
PDFDATA.io Uses Pallet with jclouds EC2 Clojure features to bootstrap PostgreSQL, Compojure, etc.
Rackspace Uses jclouds as their Rackspace Cloud SDK for Java
Red Hat Uses jclouds to deploy OpenShift Flex applications to Terremark, Rackspace, and EC2
Roboconf Uses jclouds in target handlers for various cloud providers
RunDeck integration Uses ComputeService as a resource provider for runbook automation
Salesforce Uses jclouds to provision servers for their automation stacks
SeatYourself Uses BlobStore to persist data
Twitter Uses jclouds infused Pallet to deploy their storm platform to standard and variable count of spot EC2 instances and Apache Whirr to set up test Cassandra clusters