As an alternative to spiders you might try
Browse3d. It can forward cache up to 180 pages at a time, has a pretty cool GUI (rotating, configurable three-dimensional cube with the pages laid out on it; picture a Rubik's Cube covered in web pages instead of coloured squares.)
You can configure one page to contain thumbs of up to (I think) twenty-five pages at a time, and highlight each one for details. Lots of neat shit.
Downside: prolonged use can cause major headaches due to your eyes adjusting to a "three dimensional" interface which is in fact flat ... makes you get queasy when you look at the actually 3-D world after looking at the simulated 3-D for four or five hours. This may not be a universal thing however; I do get it when using Browse3D, the ROOMS desktop UI, some first-person-shooter video games, etc. Obviously not everyone suffers the same problem or the products would likely not exist.
Phaedrus