What makes a good logo?

Let it be simple and must speak out for the site by itself and should perfectly blend into the site.

I find a really good "Simplicity Test" is to Invert the colors.

Completely screwing up the colors shouldn't destroy your design. So if your design is still recognizable it's probably simple and well balanced. Sometimes the colors still work and you end up with another color combination, or colors you didn't think of.

Very good guidelines mentioned previously, though.

I'd like to add that minimalism is a growing trend in the industry (check out examples like the new Starbucks logo, Nike, Apple, Google, Gap, Volkswagen, etc.). Less = more. Keep it simple.

Also, remember that it must relate to your product & audience, be memorable, and thought-provoking. Good luck!

It needs to be clean, crisp, related to the industry / business and look appealing on the eye. This means don't use sharp fluorescent colors. Think curves and smooth gradients. Also make sure its memorable and if you can... try and make it really clever. Like the FedEx arrow in their logo and the A to Z of the Amazon logo. Little clever ideas.

Start off with a mind map, note down everything you have in mind, possible clever tricks within the logo, colors etc.

You can get loads of inspiration from CSS galleries such as www.creattica.com that might feed you with ideas. And also check out color palettes for the logo over at http://www.colourlovers.com/

Hope this helps!

It is a misconception that a logo should be clear (as in 'that is clearly a soft drink logo'). Do you think that the Coca Cola logo was developed to reflect a soft drink? It is the other way around.

Whatever you decide to design, always make sure that when you invert the colors (ie make a black and white version of it for things such as Faxes etc), that the logo is still legible and still brings its message across.
The general rule of thumb regarding logo design is SIMPLICITY. You don't want to create something with lots of intricate detail.

Something else I remember from when I was studying design was that the lecturer also advised us against using gradients. The reason for this is because, lets say now you want to embroid the logo onto a t-shirt, there is no way that you would be able to get that gradient to come thru on the embroidery. I always keep this in mind - just in case

CreativeDesigns brings up a good point about the gradients. Not only will they not look good on an embroidered design, but they also don't translate well to photocopies. When everyone else has said that a logo should look good in black and white, that's true black and white with no grayscale in there.

Someone may have already said this but I guess it won't hurt to reiterate – Simplicity and the logo's relevance to the industry or business are important characteristics of a good logo. Just look at the most successful logos out there – Nike, Adidas, Apple, etc. - to prove this point.

Unique, Eye catching, Simple, colorful.

A good Logo should be Simple, Memorable, Appropriate. If you look at a Logo, and can tell what kind of company or service it represents in 3 seconds, than it is a quite good logo.