string URLtoList = "http://URLTOLIST";

using (SPSite ListSite = new SPSite(URLtoList))
{
    // Check for null
    if (ListSite == null)
    {
        throw new SPException("Unable to locate site.");
    }

    // Get the List Web
    using (SPWeb ListWeb = ListSite.OpenWeb())
    {
        // Check for null
        if (ListWeb == null)
        {
            throw new SPException("Unable to open web.");
        }

        // Get the List
        SPList TheList = ListWeb.GetList(URLtoList);

        // Check for null
        if (TheList == null)
        {
            throw new SPException("Unable to find list.");
        }
        else
        {
            // You can now use "TheList" referance from nothing more than a URL to the List
        }
    } // SPWeb.Dipose();
} // SPSite.Dispose();