When it comes to memorable logos, the ones that are easily recognizable and remembered are the most simple. Think about it: what could be more simple than Target’s red bulls eye? Or the Nike swoosh? Both simple, both very effective logos that are recognized internationally. And, both logos work well in color and in black-and-white. That’s another key element of good logo design – you never how people will see your logo. You want it to make sense whether someone has photocopied it, or if someone is color blind. You shouldn’t discriminate! Make it clear for everyone.
Here are some examples I’ve gathered of good logos that are simple, yet effective:
This one for Loop Consulting has nice coloring, but obviously its biggest draw is that the name is one continuous loop. I like logos that can bring in an element of the company’s name.

Another example of a logo using a name is from Watermelon Event Management. I like how the “watermelon” and stage look come together. Very good. I never would have thought a watermelon could look like a stage!

Another simple concept for a logo comes from a woman’s clothing store: Reveal. Although, the name of the store makes me think it’s a lingerie store and this logo looks like too graceful to be for a lingerie store!

Lastly, this African Film Club logo also catches my eye with the colors and the piecemeal look of the country. Nice usage of colors as well – colors that are often seen and associated with Africa. So simple, but so clear and effective.

Logos must be: memorable, effective without color and scalable (that is, it should work whether it’s scaled to 1-inch tall [letterhead] or 10-foot tall [billboard]). Good logos are readable, distinctive and they must have staying power. You don’t want to change your logo every few years – your logo is what people recognize you by. Look at Pepsi and Pizza Hut – they’ve both been in business for a long time and haven’t changed their logo very often at all. I believe that Pepsi has changed maybe every 20 years or so. Make sure your logo isn’t too trendy so that you don’t have to change it every few years. Overall, be sure your logo’s “feel” gives off what you want customers to feel when they see or think about your brand. As a divorce lawyer, you wouldn’t want a clown face in your logo and as a children’s photographer, you wouldn’t want a nature scene as your logo. Make sure your logo fits your company’s personality.
Uniqueness is a great point. Sometimes I wonder how possible it is to create an entirely unique logo. Sure, you can create one that’s unique to you, but to create one that no-one else has never created is another thing altogether.