Even this site, honestly, is less than easy to deal with on a recurring basis. (Consider, hard to remember which was the top story three days ago at noon.) Specifically, sometimes I lose a story because I refresh and something plummeted off the page. Hard to have any idea how far to "scroll back" to see it.
I remember when it was "new-fangled" (and DHTML anyone?) and everyone put those annoying cursor trackers that trailed blobs from where your cursor was.
What I mainly remember is two things: suddenly everyone had to do client-side form checking to prevent people from typing dashes in a phone number field, and everyone tried to imitate Java without actually using Java. It seems like any way you could enhance a page by combining mouseover events, gifs and loading content dynamically you would throw into a page, even if it made the user experience a total mess. Which of course never happens today.
My favorite memory is helping to write some of the first "griefers" using JS. If you were unlucky enough to stumble onto our page you had a window literally jumping around your screen with pop-ups til the end of time. There was no way to exit the browser until you'd clicked it all and it'd never end. Just getting your mouse near the 'X' would make the window jump around again. Of course, that was a mild annoyance compared to loading fonts and images so big they'd consume all the available RAM and make the machine fall over from swapping in about 15 seconds.
I remember those myriads of mouseover buttons.