I don't care for toolbars much myself. I like to minimize the space consumed by my broser, so there's not much more than the regular menu, address bar, and my tabs. (And I use the F11 key in FireFox, if I need even more browser-space clear of clutter.)

Here's how I consider it:

If it piggybacks along with something else (another program, or some web-service) It's going in the malware category. (Spyware is a type of malware in my opinion.) If it asks whether I want it and abides by that decision, then it's in the grey area of malware. (At least then it plays by the rules, but is likely something I don't want/need anyways.)

Now if it's something you have to specifically look for on its own, isn't excessively pushed by its maker (no spamming, heavy advertizing, link farms, or other underhanded kind of crap associated with it), and only installs as a standalone software - it's probably more of a utility or add-on than malware. (Like some Firefox extensions.) But even then, if it does any of the things Analog-X64 mentioned, right back into the malware side.

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Barbequed Pixels?

Your friendly neighborhood Wings3D nut.
Also feel free to browse my freebies at ShareCG.
There might be something worth downloading.