A common form of dispersal for spiderlings is something called "ballooning". They hatch out of their egg sac, all 300+ of them if they're widow spiders, and climb the nearest structure - a tree, a building - and take a flying leap. Well, let me back up. They don't exactly jump. They send out one or more long silk trailers, and the wind - whatever wind there is - will engage it and elevate their light little bodies up and into the air for fate to do with them as she pleases. It's really quite beautiful, if you're not standing underneath them.
If only life could be so simple... :)
There is a fair amount of serendipity needed in this method. Several of the little guys get picked off by predators while embracing their moment in the wind. Being in the right place at the right time, having it coincide with precisely what you want... There's a magic elixir in that, and when it's there, it's so, so sweet.