Using a SharePoint feature, webparts can be deployed to SharePoint webparts gallery.

Feature.xml:

<?xml version="1.0" encoding="utf-8"?>
<Feature
    Title="MyWebparts"
    Description="Description for my webparts"
    Id="[GUID]"
    Scope="Site"
    Hidden="FALSE"
    DefaultResourceFile="core"
    xmlns="http://schemas.microsoft.com/sharepoint/">
  <ElementManifests>
    <ElementManifest Location="Webparts.xml" />
    <ElementFile Location="MyWebpart1.webpart" />
    <ElementFile Location="MyWebpart2.webpart" />
    <ElementFile Location="MyWebpart3.webpart" />
  </ElementManifests>
</Feature>

Webparts.xml:

<?xml version="1.0" encoding="utf-8" ?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
  <Module Name="WebPartPopulation" Url="_catalogs/wp" RootWebOnly="TRUE">
    <File Url="MyWebpart.webpart" Type="GhostableInLibrary">
      <Property Name="Group" Value="MyGroup"></Property>
      <Property Name="QuickAddGroups" Value="MyGroup" />
    </File>
    <File Url="MyWebpart2.webpart" Type="GhostableInLibrary">
      <Property Name="Group" Value="MyGroup"></Property>
      <Property Name="QuickAddGroups" Value="MyGroup" />
    </File>
    <File Url="MyWebpart3.webpart" Type="GhostableInLibrary">
      <Property Name="Group" Value="MyGroup"></Property>
      <Property Name="QuickAddGroups" Value="MyGroup" />
    </File>
  </Module>
</Elements>

Download:

Click here to download Sample Feature with one ContentEditorWebpart which is named "HelloWorld.dwp."