Short, sweet and catchy domain names — they're mostly taken. But if it makes sense to include a number somewhere in the attention-grabbing website you're setting up, you can break into the four-letter walled garden.
The semmyfun blog points out that something near 85 per cent of all possible domains with three letters and one number are available, which is actually better odds than having two letters and two digits. Hyphens, too, break out of the short name prison, but there's more likelihood of domain confusion there. As for finding a good, creative name, we've previously recommended Bust a Name and Domainr to get started. [semmyfun]