You can develop application page and 'pop it up' by using Dialog framework on button/icon/link click event you included in masterpage (or where you need it).
In application page you add textbox for body and on PageLoad you set it's default value (current page URL):
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
textBoxBody.Text = System.Web.HttpContext.Current.Request.Url;
}
You also add textboxes for mail address of recipient and subject (if needed) as well as additional Send button:
<asp:button ID="SendMail" runat="server" Text="Send" OnClick="SendUrlinMail" />
And in application page code behind:
protected void SendUrlinMail(object sender, EventArgs e)
{
SPUtility.SendEmail(SPContext.Current.Web, false, false,
textBoxTo.text, textBoxSubject.text, textBoxBody.Text);
}
Since you are using SPContext.Current.Web
from field of your message will be current users mail (if exist) - this is something I can only verify by experience (!)
This is simplest solution I can think of. Sry - no jQuery :)