Evan Williams has a very good post on evaluating product ideas based on his previous experience (launching Blogger, Odeo - pretty much forgotten in that article - and Twitter). I’ve been thinking about a couple of products as well (have been for a while, actually), so the whole article sort of fell into place with my own criteria. Here are Ev’s:

• Tractability: How difficult will it be to launch a worthwhile version 1.0?
• Obviousness: Is it clear why people should use it?
• Deepness: How much value can you ultimately deliver?
• Wideness: How many people may ultimately use it?
• Discoverability: How will people learn about your product?
• Monetizability: How hard will it be to extract the money?
• Personally compelling: Do you really want it to exist in the world?

To these I would add two other characteristics that I believe have a great impact on a product’s success: cleverness and trustworthiness. You know when a product is clever because you get the feeling of empowerment and delight. And trustworthiness (although perhaps difficult to assess initially) defines how people look at your product or service - if users can trust it, it is more likely that they’ll become engaged and use it often. People are often skeptical about things that dip into their personal affairs (think Facebook’s Beacon and why it sucks), but will feel at ease to engage and discover new things about a product if they trust it.

Ultimately, it isn’t easy to determine the likeliness of a product being successful by putting it to the test against a series of attributes - but it may help. I’m still a big fan of entrepreneurs following their gut and seeing where it takes them, but depending on the person, that might not be a good plan to stick to.

I definitely recommend you give Ev’s article a read if you’re an entrepreneur - you’re still here so chances are you’ll be interested. Unfortunately Evan still doesn’t allow comments on his blog, because I would imagine the discussion on such an article would be interesting.