Create a web part to show sites and sub-sites
Saw a newgroup question the other day about how to do this in SharePoint 2007. While the solution posted works quite well here is some code that I wrote that should accomplish what the user needs. This will either start at the root of your site collection or a specified location (which may or may not be the site you are on). It will then add all the sites and sub-sites to a treeview control, security trimmed of course. Note that it uses recursion to view all the sub-sites so depending on how your system is architected this may take a while. Guess a simple enhancement would be to add a parameter to limit the depth of your treeview. You could get even more fancy and show X levels by default and then if you expand beyond that add the nodes dynamically. 
using System;
using System.Runtime.InteropServices;
using System.Web;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.WebControls;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using Microsoft.SharePoint.WebPartPages;
using Microsoft.SharePoint.Publishing.Navigation;
namespace GBushey.Portal.SiteMap
{
[Guid("1e900b56-1f33-4772-b5b9-9df73612c40d")]
public class PortalSiteMap : System.Web.UI.WebControls.WebParts.WebPart
{
string _StartNodeName;
bool _StartAtTopLevel = false;
[WebBrowsable(true),
Personalizable(PersonalizationScope.Shared),
FriendlyName("Start at the Root Node?")]
public bool StartAtTopLevel
{
get
{
return _StartAtTopLevel;
}
set
{
_StartAtTopLevel = value;
}
}
[WebBrowsable(true),
Personalizable(PersonalizationScope.Shared),
FriendlyName("The name of the root level site")]
public string StartNodeName
{
get
{
return _StartNodeName;
}
set
{
_StartNodeName = value;
}
}
protected override void CreateChildControls()
{
this.ChromeType = PartChromeType.None;
try
{
if (_StartAtTopLevel || _StartNodeName.Length > 0)
{
PortalSiteMapDataSource siteMapDataSource = new PortalSiteMapDataSource();
siteMapDataSource.TrimNonCurrentTypes = Microsoft.SharePoint.Publishing.NodeTypes.Page;
siteMapDataSource.TrimNonCurrentTypes = Microsoft.SharePoint.Publishing.NodeTypes.List;
base.CreateChildControls();
PortalSiteMapProvider portalSiteMap = new PortalSiteMapProvider();
portalSiteMap.IncludePages = PortalSiteMapProvider.IncludeOption.Never;
portalSiteMap.IncludeHeadings = false;
portalSiteMap.EncodeOutput = true;
SiteMapNode startNode;
if (_StartAtTopLevel)
{
startNode = portalSiteMap.RootNode;
}
else
{
startNode = portalSiteMap.FindSiteMapNodeFromKey(_StartNodeName);
}
SiteMapNodeCollection nodes = portalSiteMap.GetChildNodes(startNode);
SPTreeView siteTreeView = new SPTreeView();
siteTreeView.ExpandDepth = 10;
siteTreeView.Nodes.Add(new TreeNode(startNode.Title, startNode.Url, "", startNode.Url, ""));
TreeNode topNode = siteTreeView.Nodes[0];
ProcessWeb(topNode, nodes);
Controls.Add(siteTreeView);
}
else
{
Controls.Clear();
Label errorMessage = new Label();
errorMessage.Text = "Enable the web part to start either at the root node or at a specific Url";
Controls.Add(errorMessage);
}
}
catch (Exception ex)
{
Controls.Clear();
Label errorMessage = new Label();
errorMessage.Text = "There was an error in the code. Please contact your system administrator and rely the following " +
"message: " + ex.Message;
Controls.Add(errorMessage);
}
}
private void ProcessWeb(TreeNode topNode, SiteMapNodeCollection nodes)
{
try
{
foreach (SiteMapNode currentMapNode in nodes)
{
TreeNode currentNode = new TreeNode(currentMapNode.Title, currentMapNode.Url, "", currentMapNode.Url, "");
if (currentMapNode.ChildNodes.Count > 0)
{
ProcessWeb(currentNode, currentMapNode.ChildNodes);
}
topNode.ChildNodes.Add(currentNode);
}
}
catch (Exception e)
{
}
}
}
}