The following code shows how to use the ListViewByQuery control in a Web Part.
Note: The code also includes a CAML query statement that is used by an SPQuery object to set the items to be displayed in the ListViewByQuery control.

protected override void CreateChildControls()
{
  SPWeb thisWeb = SPContext.Current.Web;
  SPList tasks = thisWeb.Lists["Tasks"];
  ListViewByQuery listTasks = new ListViewByQuery();
  listTasks.List = tasks;
  SPQuery taskQuery = new SPQuery(listTasks.List.DefaultView);
  taskQuery.ViewFields = "<FieldRef Name='Title' /><FieldRef Name='Due' />";
  taskQuery.Query = "<Where><Leq><FieldRef Name='Due' /><Value Type='DateTime'>"
    + SPUtility.CreateISO8601DateTimeFromSystemDateTime(DateTime.Now.AddMonths(1))
    + "</Value></Leq></Where>";
  listTasks.Query = taskQuery;
  this.Controls.Add(listTasks);
  base.CreateChildControls();
}

The following code shows how to extract the selected people in a PeopleEditor control.
Note: The code runs in a Visual Web Part, and relies on there being a PeopleEditor control named peoplePicker, and an ASP.NET ListBox control called selectedPeople

namespace SharePointControls.ControlExample
{
  public partial class ControlExampleUserControl : UserControl
  {
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void getPeople(object sender, EventArgs e)
    {   
      string allPeople = peoplePicker.CommaSeparatedAccounts;
      string[] selected = allPeople.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
      foreach (string p in selected)
      {
        selectedPeople.Items.Add(p);
      }
    }
  }
}

The following code shows how to use the SPGridView control in a Web Part to display list items from a list:

protected override void CreateChildControls()
{
  SPGridView taskGrid = new SPGridView();
  taskGrid.AutoGenerateColumns = false;
  BoundField taskTitle = new BoundField();
  taskTitle.DataField = "Title";
  taskTitle.HeaderText = "To Do...";
  taskGrid.Columns.Add(taskTitle);
  SPWeb thisWeb = SPControl.GetContextWeb(Context);
  SPList taskList = thisWeb.Lists["Tasks"];
  SPDataSource listSource = new SPDataSource();
  listSource.List = taskList;
  SPDataSourceView view = listSource.GetView();
  taskGrid.DataSource = listSource;
  if (view.CanSort) 
  {
    taskGrid.AllowSorting = true;
  }
  taskGrid.DataBind();
  Controls.Add(taskGrid);
  base.CreateChildControls();
}