Hello Marko,
I found this post that might help you along

http://our.umbraco.org/forum/developers/api-questions/8828-Get-Properties-from-Member-in-Umbraco-programmatically

Best

danielcruger.comhttp://our.umbraco.org/forum/developers/api-questions/8828-Get-Properties-from-Member-in-Umbraco-programmatically

Thanks for your help Dan.

In the end, I ended up using code from another post (which I've lost the link to).

Either way, here it is.. It's basically a custom extension that selects members by Group Name/Id and allows me to use XSLT for the output.

using System;
using System.Data;
using System.Data.SqlClient;
using System.Text;
using System.Xml;
using System.Xml.XPath;
using Microsoft.ApplicationBlocks.Data;
using umbraco.cms.businesslogic.member;

namespace Custom_Controls.xsltExtensions {

    public class customExt
    {
        public static XPathNodeIterator GetMembersByGroupName(string groupName)
        {
            try
            {
                return GetMembersByGroupId(MemberGroup.GetByName(groupName).Id);
            }
            catch (Exception ex)
            {
                XmlDocument xd = new XmlDocument();
                xd.LoadXml("<response><success>false</success><error>" + ex.Message.ToString() + "</error></response>");
                return xd.CreateNavigator().Select("/response");
            }
        }
        public static XPathNodeIterator GetMembersByGroupId(int id)
        {
            XmlDocument xd = new XmlDocument();

            try
            {
                DataSet ds = SqlHelper.ExecuteDataset(
                        new SqlConnection(umbraco.GlobalSettings.DbDSN),
                        CommandType.Text,
                        @"
                                                Select ccx.xml 
                                                from cmsContentXml ccx 
                                                        inner join cmsMember cm 
                                                                on ccx.nodeId = cm.nodeId                                       
                                                        inner join cmsMember2MemberGroup cm2mg
                                                                on cm.nodeId = cm2mg.Member
                                                Where cm2mg.MemberGroup = @group
                                        ", new SqlParameter("@group", id.ToString()));

                StringBuilder sb = new StringBuilder();
                sb.AppendLine("<root count=\"" + ds.Tables[0].Rows.Count + "\">");

                foreach (DataRow dr in ds.Tables[0].Rows)
                {
                    sb.AppendLine(dr["xml"].ToString());
                }
                sb.AppendLine("</root>");

                xd.LoadXml(sb.ToString());

                return xd.CreateNavigator().Select("/root");
            }
            catch (Exception ex)
            {
                xd.LoadXml("<response><success>false</success><error>" + ex.Message.ToString() + "</error></response>");
                return xd.CreateNavigator().Select("/response");
            }
        }
    }
}

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