I'd use POST for an array.

Try creating a RouteValueDictionary holding your values. You'll have to give each entry a different key.

<%  var rv = new RouteValueDictionary();
    var strings = GetStringArray();
    for (int i = 0; i < strings.Length; ++i)
    {
        rv["str" + i] = strings[i];
    }
 %>

<%= Html.ActionLink( "Link", "Action", "Controller", rv, null ) %>

will give you a link like

<a href='/Controller/Action?str0=val0&str1=val1&...'>Link</a>

You can then use the ValueProvider and select all of the keys that start with str.

public ActionResult Action()
{
    var strKeys = this.ValueProvider.Keys.Where( k => k.StartsWith("str") );

    foreach (string key in strKeys)
    {
        ...
    }
}