iOS: The Share Extension makes it pretty easy to email contacts from any app in iOS, but you still have to go through a list or start typing a name. Bee allows you to create a favourite list so you can quickly tap and send an email.
Once you set up Bee with your favourite contacts, you can tap the Bee Share Extension, select your contact, then email away. You can also group contacts together for group messages if you tend to send messages to a list. It's a simple idea, but if you really use that Share Extension a lot, it makes it much quicker. You can check out how it works for free, but if you want more than one contact you'll need to pay $2.49.