gistfile1.cs

    public class QueryString {
        Dictionary<string, string> parameters = new Dictionary<string, string>();

        public QueryString Add<T>(string key, T value) {
            parameters.Add(Uri.EscapeDataString(key), Uri.EscapeDataString(value.ToString()));

            return this;
        }

        public QueryString Add<T>(Dictionary<string, T> p) {
            foreach (var entry in p) {
                Add(entry.Key, entry.Value);
            }

            return this;
        }

        public string Build() {
            var queryString = new StringBuilder();

            foreach (var entry in parameters) {
                if (queryString.Length > 1) {
                    queryString.Append("&");
                }

                queryString.AppendFormat("{0}={1}", entry.Key, entry.Value);
            }

            return queryString.ToString();
        }
    }