My maven settings file

settings.xml

<settings>
<mirrors>
  <mirror>
    <id>nexus</id>
    <mirrorOf>*</mirrorOf>
    <url>http://si.io8.org/nexus/content/groups/public</url>
  </mirror>
</mirrors>

  <profiles>
    <profile>
      <id>is-nexus</id>
      <!--Enable snapshots for the built in central repo to direct -->
      <!--all requests to nexus via the mirror -->
      <repositories>
        <repository>
          <id>central</id>
          <url>http://central</url>
          <releases><enabled>true</enabled></releases>
          <snapshots><enabled>true</enabled></snapshots>
        </repository>
      </repositories>
      <pluginRepositories>
        <pluginRepository>
          <id>central</id>
          <url>http://central</url>
          <releases><enabled>true</enabled></releases>
          <snapshots><enabled>true</enabled></snapshots>
        </pluginRepository>
      </pluginRepositories>
    </profile>

    <profile>
      <id>jdk-1.6</id>
      <activation>
        <activeByDefault>true</activeByDefault>
        <jdk>1.6</jdk>
      </activation>
      <properties>
        <maven.compiler.source>1.6</maven.compiler.source>
        <maven.compiler.target>1.6</maven.compiler.target>
        <maven.compiler.compilerVersion>1.6</maven.compiler.compilerVersion>
      </properties>
    </profile>

  </profiles>
  <activeProfiles>
    <!--make the profile active all the time -->
    <activeProfile>is-nexus</activeProfile>
  </activeProfiles>
</settings>