Is there any easy way to share links between iPads? For example, if my friend is looking at something interesting and wants to send it to me. Is email still the best way?
Email is probably the best option. Or you could use a social network site. Something like Facebook is pretty good for stuff like that...
Yes, e-mail. There is actually no easier way on iOS.
But I'd advise setting up something like Yahoo Pipe or Twitter Mail so you can send a Carbon Copy to twitter, digg, delicious (all of which are good ways to share links) and / or google bookmarks to be able to choose to have your link into some kind of bookmarking other than private e-mails.
For compatible iOS devices running iOS 7 and later, the easiest way to share URLs (and various other items) is to use AirDrop, a feature build into iOS.
AirDrop works only on iPad (4th generation) and later running iOS 7. The complete list of compatible iOS devices can be found here.
For more details, please go through the Apple Support article, Use AirDrop on your iPhone, iPad, or iPod touch.