I have this script for wikipedia with me. It works only when you send the message. If you want, i can edit it again to make it respond to other's messages too.
code:
//Wikipedia Search Script, originally created by Paril, modified by ddunk.
//Edited by Felu(http://www.feluowns.com) for personal use.
var xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
var query;
var CurrentWindow;
var url;
var title;
var response;
var result;
function OnEvent_ChatWndSendMessage(pChatWnd, sMessage)
{    
    if(sMessage.substr(0,5) == "!wiki")
    {
        CurrentWindow = pChatWnd;
        query = sMessage.substr(6,sMessage.length);
        get_wikipedia_result(query);
        return "";        
    }
}
function get_wikipedia_result(query)
{
    xmlHttp.open("GET", "http://en.wikipedia.org/w/index.php?title=Special%3ASearch&search=" + query + "&fulltext=Search", true);
    xmlHttp.onreadystatechange = stateChanged;
    xmlHttp.send(); 
}        
function stateChanged() 
{
    Debug.Trace(xmlHttp.readyState)
    if (xmlHttp.readyState==4)
    {
        Debug.Trace(xmlHttp.status)
        if (xmlHttp.status==200)
        {
            Debug.Trace("test")
            url = new RegExp("<li style=\"padding-bottom: 1em;\"><a href=\"(.*?)\"");
            title = new RegExp("<li style=\"padding-bottom: 1em;\"><a href=\".*?\" title=\"(.*?)\">");
            response = xmlHttp.responseText;
            result = response.match(url);
            title = response.match(title);
            if (result)
            {                
                CurrentWindow.SendMessage("Wikipedia search: " + query + "\n Result: " + title[1] + " - http://en.wikipedia.org" + result[1]);
            }
            else
                CurrentWindow.SendMessage("Wikipedia search for " + query + " returned no results");
        }
    }
}