I'm looking for something like frames, without it being frames.

I have a training manual composed of multiple pages and then each page is linked on the main training page and opens in a new window. This works alright, but I'm wondering if there is a theme/plugin that would allow me to create something sort of like frames, with a left sidebar of linked topics, which when clicked show up in the content area. Pre-WP, I could easily set up this in frames (I know frames are bad for SEO, but it's an internal training manual so I don't care about SEO for it)... I'm wondering if there is any theme or plugin that would function like this?