ASP.NET

<asp:Repeater ID="RP_contacts" runat="server">
<HeaderTemplate>

	<table style="margin: 0px 10px 0px 10px" cellpadding="2px" cellspacing="0px">
		<tr>
			<td style="border-bottom: solid 1px Black;"><input type="checkbox" onclick="javascript:check_all();" id="allbox" name="allbox" /></td>
			<td style="border-bottom: solid 1px Black;">Contact Name</td>
			<td style="border-bottom: solid 1px Black;">Email Address</td>
			<td style="border-bottom: solid 1px Black;"> Phone</td>
		</tr>
</HeaderTemplate>
<ItemTemplate>
	<tr>
		<td>
			<asp:CheckBox runat="server" ID="cbx" CausesValidation="true" Checked="false" />
			<asp:HiddenField runat="server" ID="HF_contact_id" Value='<%# DataBinder.Eval(Container.DataItem, "contact_id" ) %>' />
		</td>
		<td><a href="contact_edit.aspx?id=<%# DataBinder.Eval(Container.DataItem, "contact_id" ) %>"><%# DataBinder.Eval(Container.DataItem, "name" ) %></a></td>
		<td><a href="email_form.aspx?mailto=<%# DataBinder.Eval(Container.DataItem, "contact_id" ) %>"><%# DataBinder.Eval(Container.DataItem, "email" ) %></a></td>
		<td><%# DataBinder.Eval(Container.DataItem, "phone" ) %></td>
	</tr>
</ItemTemplate>
<FooterTemplate>
	</table>
</FooterTemplate>
</asp:Repeater>

public ArrayList get_checked_contacts() {
    ArrayList result = new ArrayList();
    foreach (RepeaterItem i in RP_contacts.Items) {
        CheckBox c = (CheckBox)(i.FindControl("cbx"));
        if (c != null && c.Checked) {
            result.Add(Int32.Parse(((HiddenField)i.FindControl("HF_contact_id")).Value));
        }
    }
    return result;
}