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The first two lenses I bought were a kit including:
Sigma 28-80 zoom
Sigma 70-300 zoom

I rarely use them anymore, as I am not a fan of zooms, and they aren't the greatest quality. They served their main purpose well, which was to help me determine which focal lengths I prefered. I'll occasionally bring out the 28-80 when I want an image that is soft on the edges. I haven't used the 75-300 since I bought a 200. The bag they came with gets a lot of use carrying around my 2 Canon 550EX flashes, ST-E2 transmitter and OmniBounces.

Rating: 2 out of 5 (mediocre)
Recommendation: OK for snapshots, and the 28-80 for macro when a bit of softness is acceptable or desireable

My main event / walkaround lens for a long time. One of my favorites. One advantage of the noisy autofocus is that I can tell by ear when focus has been achieved. I also have a good enough feel for composition that I don't always need to look through the viewfinder.

It is incredibly light and small.

Rating: 4 out of 5 (good)
Recommendation: If you own a Canon EF mount camera, buy this lens, even if you already own another 50.

I love the distortion and wide angle of view of this lens. It usually stays in my main bag.

Rating: 4 out of 5 (good)
Recommendation: A reasonably affordable way to get a wide angle lens. Might not be as good on a full frame camera.

These two lenses don't get much use. I'm not sure if any images from the 135 have made my portfolio. The 65 is fun, but difficult to use due to a dark image in the viewfinder when using large magnification.

Rating: 3 out of 5 (decent)
Recommendation: If you need extreme macro, or a soft portrait lens, these are good choices.

These are two of my favorite lenses. The 24 is great when doing long exposures on a tripod. The autofocus isn't very fast, and the clutch mechanism is weird. The 24 isn't very flattering for people, but can work for group shots. The main strength of the lens is landscape work.

The 85 is just plain excellent. Even though I had the money, I choose the 85 1.8 over the 85 1.2 based on image quality. The bokeh of the 1.8 just appealed to me more than that of the 1.2.

Rating: 4 out of 5 (good) for the Sigma 24, 5 out of 5 (excellent) for the Canon 85
Recommendation: The image quality of the Canon is breathtaking. It is my first choice for portraits. The Sigma is a very good choice for a moderately wide angle, I don't know if it would hold up on a full frame camera.

This is a decent lens, I use it for any handheld macro. Autofocus is horrendously slow.

Rating: 3 out of 5 (decent)
Recommendation: An affordable choice for macro and portrait work. Don't try using it for action shots!

I really like the 50 focal length on a 10D. I bought this because almost everyone says it is a huge step up from the 50 1.8. I certainly like the wider aperture, but overall I think it is just different than the 1.8, not necessarily better. One thing I learned the hard way - don't overtighten the lens shade (always use a lens shade), or it will put pressure on the lens and make it impossible to focus.

Rating: 4 out of 5 (good)
Recommendation: A very good all around lens, especially good for low light situations.

I keep a wide angle converter attached, I also have a teleconverter. I bought this to tide me over until I could get a large format camera. I would use it more if it had a wider range of movement. Once you have it focused, you can't tilt or shift much. Only one image from this lens has made my public portfolio.

Rating: 3 out of 5 (decent)
Recommendation: It isn't very expensive. If you like the "Holga" look, pick one up.

Sample image:

Lensbabies official site.

The 200 2.8L is another excellent lens. Most of my bird in flight photos were taken with this lens.

Rating: 5 out of 5 (excellent)
Recommendation: Buy it.

It certainly does make things a bit softer, but the extra reach is nice. Seems to work better with the 200 than the 300.

Rating: 3 out of 5 (decent)
Recommendation: You should probably buy the 1.4x extender before the 2x.

I'm still learning this lens. A shorter focal length would probably be better, as the movements don't seem to do much.

Rating: undecided
Recommendation: If you can, get a view camera instead. If you have more money, consider the Canon T/S line.

This has taken over for birds and other general telephoto duties from the 200, which doesn't get used as much now. The 200 has better image quality, but not as much reach. The stabilization feature really helps.

Rating: 4 out of 5 (good)
Recommendation: Much less expensive, and lighter than the 300 2.8L, but I expect I'd be happier with the 2.8.