What do you give an ex girlfriend who is getting Married?

I guess in today’s complex world this is an increasingly common dilemma. We are still on very good terms, she knows that I think her husband to be is a complete arsehole but there is a mutual understanding that we do not discuss the numerous reasons why my assessment is correct. So what to give as a present? Since the wedding is in foreign parts and I have left it too late to ship anything that restricts my options.

On the occasion of his first marriage, my Uncle Chris was given by the late David Frost, a voucher to use with a divorce lawyer. As it happens that came in handy fairly soon afterwards. But I very much hope that this would be an unwanted and un-needed gift. As such it has to be an e-book ( with a promise of a hard copy later). Any ideas?