For Fuse ESB or more general for Apache Karaf based servers you have the pax url mvn uri prefix. This allows to install bundles from mvn repositories. I propose to always use this uri instead of the file one.
In your case the command would be:
install mvn:com.helloworld/Helloworld/1.0.0-SNAPSHOT
This uri is even a little smaller than the file based one. The big adavantage though is that you have the full mvn resolution available. So this above url will work for bundles from your local maven repo but also from maven central.
Of course you typically will not deploy your own artifacts to maven central. So if you want to use this inside your company you should set up a maven repository like Nexus or Archiva. Then you deploy your own bundle using mvn clean deploy into your company repo. Of course this will require that you set up your pom correctly but you will need that anyway for any larger project.
The last step needed is then to set up your Fuse ESB / Karaf to also use your company repo. This is done by adding the repo uri to the file etc/org.ops4j.pax.url.mvn.cfg.
Of course this is a little more work than the http url that Neil proposed. THe advantage is that this will integrate very well with your maven build process and it will make your bundle mvn uris independent of the location of your maven repo. It will also allow you to mix your own bundles and open source bundles when you start to combine them using features.