I mean literally free points, just for signing up. I am not for a minute going to provide a comprehensive list here, but this is my starter for 10: Etihad Guest - 500 miles Airberlin Topbonus - 500 miles Heathrow Rewards - 100 points Any more for any more?
While obviously you should grab anything you can when signing up, I'd say these small sums rarely affect whether it is a good deal. The last (really great) offer that I signed up to a new scheme for (and it was open to all members) was the ClubCarlson 50k offers a few years ago.
That was a classic. I recall IHG have given points on sign up in fairly decent chunks in the not-too-distant past, too.