ok - i'm in the process of trying to obtain a .com domain that has expired, I have the .org and the .net & .info are registered by someone else is it worth my time grabbing any of the others if I do/don't get the .com? I could also get the .com.au (.co.uk is taken)
The .com domain names are still quite valuable. The .com.au would be relevant if your site caters to the Australian audience. If it is a valuable name and you want to protect your namesake then getting all the variants would make sense. Some multinationals are doing that.
After the COM, the best option is going for NET, ORG, INFO and BIZ. WS, and NAME sometimes are valuable but not as a dot.com and, of course, county level domains when your content is targeted to "X" audience or region.
Unless your primary intent is for a hosting/isp related offering or similar, I wouldn't bother registering the alternate extensions right now. If you do manage to grab the domain, then you might look into it. Any extension can be built into a good site, but the .com domains are definitely going to be worth more and in the vast majority of cases will bring you the most "type in" traffic. Heck, though, with .org going for less than 3 bucks with a lot of registrars and .info on sale right now for a buck or less each.... why not grab them too. Contradicting myself, I know, but even if you don't snag the primary name you're interested in, you can use these to boost the one you do get. I registered just over 600 info names with directi (resellerclub) specifically for this purpose and to potentially get a bit of banner ad views as well. Anyway, good luck on snagging that name. And remember, if a kiter grabs it, keep a close look out over the following 4-6 days... it just might be available again then. As always, these are just my humble opinions. Best Wishes to all.
If you are planing to develop a business then it's very worth it. If the price is low and the domain is good it can be worth paying for it. It can increase the value as a package.
Agree with eddy2009. .com.au's are prob best if you are planning to geo-target. Also depends on your marketing strategy and how involved you are. Generics are great for type-ins and initial traffic, and brandnames take longer to build and are tied to the quality of your site.