Cone wrenches are to access flats on axles where very little of the axle is exposed. It is similar to an open-ended wrench but much thinner: typically about 2 mm thick, compared to approximately 7 mm for a standard open-ended wrench. The "cones" are your bearing races for your axles.
http://commons.wikimedia.org/wiki/File:ConeWrenches.jpg
Headset wrenches are oversized (32 – 36 mm) flat open-end wrenches for tightening headset cups and lock nuts on threaded steering tubes. May be designed to contact 7 sides of an 8 sided (8-point) lock nut. You can sometimes use them on bottom brackets as well. I have a 4-in-1 wrench like this:
http://www.ukbikestore.co.uk/product/38 ... -in-1.html
Bottom bracket wrenches are special because on one-piece cranks, sometimes there is a big threaded washer that tightens up the bottom bracket bearing race (left side) and this particular wrench is waaaaay easier than using a screwdriver and a hammer.
http://www.flickr.com/photos/eoorider/5300948164/
A pin spanner allows you to tighten/loosen the bearing race much easier as well.
http://www.bikepartsplace.com/discount/ ... pa-1c-grn/
the bike specific wrenches are thinner than standard wrenches and make the job much easier. You can use regular size wrenches on most jobs, but not all of them. I have found as I have bought more bike specific tools, it just makes it easier and faster, and when doing the Target thing, the quicker I get them assembles and correctly adjusted, the better.
Performance does carry most of the tools individually, and it can cost a bit to get them piece by piece. But if you get the repair sets, they have a lot of what you don't need. We're doing cruisers (for the most part) and we don't need all the multi-gear specific tools...at least I don't. The Park cone wrenches with the blue handles are easier on your hands than the cheaper Pedro's tools they sell. Pedro's also has Park quality (i.e. bike shop quality) tools as well, but they are a little pricier and harder to find.
glad to help,
jeff