For domain names, how important is .com these days? Do you believe that a memorable name is more important?
Sure, people tend to look down at some top level domains ( .biz comes to mind), but what about .tv , .me & .ly ? Is it too early for the consumer population to remember these alternative tlds?
Hypothetical scenario - your companies product is focused around friends, and all the good friend related .com name's are taken (friend.com as well).
Which approach would you take?
What is the purpose of the web site and who is the target audience? If you are trying to sell something, or just deal with the general public .COM is the only choice. How many times have you mistyped someone's email address because it ended in .net or .org? You mistype the email address because you have been trained, since the day you first went on the internet, that all internet addresses end in .COM.
A .COM address is reliable, trustworth, and normal.
The .NET and .ORG addresses are odd, but acceptable. Nowhere near as good as .COM though.
The .EDU and .GOV addresses don't count since you can't really get one of those.
Any other address is suspect. It is not normal. Why trust something strange? Other addresses scream "I couldn't do better than this. I'm desparate, so this is what I got."
There are a few odd names here and there that are successful without .com, such as bit.ly, or justin.tv, or last.fm. But, I'd agree with most of the people than answered, that a .com certainly increases the probability that you will be more memorable to customers.
The .com TLD is essential because it's the gold standard of the web today. This is what mainstream business use and what users are will always type by default.
This question should have been asked like "What type of TLD is more important, .com or .net or others?"
If you plan to make money out of your site then without doubt .com is required. TLD and domain name are entirely different things and should not be compared for importance as both are important.
From my answer on another page :
The advantages of .COM is that if people only remember the name of
your "product" and not the url, it is way more likely that they will
go .COM then .NET
Also, some users like to use Ctrl + Enter when
they type in the address bar, which automatically inserts a .COM to
it.