Hi chasm54,

Congrats on the new bike. Here is a good place to start your research in dynamo rectifiers device chargers.

Basically there are 2 types on the market. One that has a built in battery and one that doesn't have a built in battery.
The types that have built in batteries store the charge generated by the dynamo and then the battery charges the desired device.
The types that don't have batteries built in just regulate the voltage from the dynamo and sends it straight to the desired device.

If you're trying to charge a iPad or iPhone then i'd suggest you go with charger with a built in battery. Reason being that when the bike stops rolling you won't have the charging of the device cut in and out.

I don't think using a bike dynamo to charge a laptop is practical.