Proper way to get all lists of a certain type from an entire site collection regardless of current location

Question

I'm creating a webpart that gives the user a feed of any annoucement list in the entire site collection, so they can aggregate data to a central portal.

I'm currently using the following, but can't find a best practice or solid pattern and want to know if it's wrong:

static public List<SPListMeta> AllSiteAnnouncementsLists()
{
    var returnList = new List<SPListMeta>();
    var collWebs = SPContext.Current.Web.Site.WebApplication.Sites[0].OpenWeb().GetSubwebsForCurrentUser();
    //GetSubWebs igonores root web, so this is a fill in
    if(SPContext.Current.Site.RootWeb.DoesUserHavePermissions(SPBasePermissions.Open))
    {
        var collSiteLists = SPContext.Current.Site.RootWeb.GetListsOfType(SPBaseType.GenericList);
        returnList.AddRange(from SPList oList in collSiteLists 
                                    where oList.DoesUserHavePermissions(SPBasePermissions.ViewListItems) 
                                    && oList.BaseTemplate == SPListTemplateType.Announcements 
                                    select new SPListMeta(oList));
    }
    foreach (SPWeb oWebsite in collWebs)
    {
        if (oWebsite.DoesUserHavePermissions(SPBasePermissions.Open))
        {
            using (oWebsite)
            {
                var collSiteLists = oWebsite.GetListsOfType(SPBaseType.GenericList);
                returnList.AddRange(from SPList oList in collSiteLists 
                                    where oList.DoesUserHavePermissions(SPBasePermissions.ViewListItems) 
                                    && oList.BaseTemplate == SPListTemplateType.Announcements 
                                    select new SPListMeta(oList));
            }
        }
    }
    return returnList;
}