The Grazing Web Broswer for iPad and iPhone is really smart about opening new tabs. If Grazing can see a link in your clipboard, it offers to open that link when you create a new tab, among other options like doing a web search or opening one of your existing bookmarks.
Grazing, built by Thinkbitz Software Studio, offers plenty of handy tab options as well. You can choose to open new tabs next to the page you are currently viewing (or at the far right of all your tabs), choose whether bookmarks open in new tabs, and pick between displaying tabs as thumbnails or, well, traditional tabs.
Another clever feature: Thinkbitz created a Grazing Push service, which is basically its version of Chrome to Phone. Add a bookmarklet to your desktop browser, and you can push any page you’re viewing to Grazing on one or more of your iOS devices.