Depends on what you mean by online. If anything internet related counts, it was e-mails I got from teachers at university. That was totally new at the time and only people in computer science and related courses had access.

My first multimedia experience was with Usenet. The internet access was from a terminal account on a UNIX host. I had to telnet into that from a Windows machine (3.1 had just come out). There was this post in several parts named "cute girl getting it up the ass". I had to download all the posts as text files, stitch them together in an editor and uudecode the whole thing. Then i had to ftp it to the Windows machine and install a JPEG viewer on that (similar procedure). Then i could finally open the Jpeg, which took about a minute on that machine. The girl wasn't actually that cute.