Passive components are great. Capacitors and resistors don't generally become obsolete. Mechanical components, if high quality are an even better deal: good switches and pots are expensive. Simple semiconductor devices -- LEDs, diodes, power transistors are not going out of style any time soon.
With ICs it is more of a gamble. There are some jellybean parts like opamps and regulators that will probably be useful, but the shelf-life of a microcontroller is limited, and a special purpose IC like a graphic LCD driver even more so. If you happen to work on a project where you have just the right specialized part, it will be great, but if the whole lot were spools of 500 each of a bunch of specialized ICs, I wouldn't take it for free. Also keep in mind that for things like LCDs and LCD drivers you may not even be able to get the documentation for the part -- if you can even identify it. There may also be required components missing that you can't get in quantities less than 1000.
In the end, as long as you have a cheap and legal way to dispose of parts you can't use (assume it all contains lead), it is probably worth the $100. Of course, if sorting through a pile of 30,000 pieces of random electronics junk looking for the hidden jems is not your idea of a good time, just buy what you want from digikey or ebay.