Hyperlinks are great to use, they allow you to grant access to websites that are far larger, more interactive and more useful than any email, PDF or JPEG file.
You can use links in Text (SMS) messages or email messages allowing the person to receive that message and click on the link at their convenience.
You can also use a url shrink site that will allow you to shrink down the size of the link so that you can send it with space to spare in a text message.
Links are an awesome way to communicate and get information out to everyone in a fast, convenient and efficient way. You can also use links for registration, online giving, surveys and anything else you can think up!