Not only does it take a while to qualify for Adsense, there is a bit of a probability that you will be shut out of the program if you violate its Terms of Service - even accidentally. So, it would be in all bloggers' best interest to delve in other monetization strategies, as it is good practice to have a diverse income stream in the event of failure in one. They also work together to net you higher profits than you might have gotten with any one of them alone.
On that note, I agree with protoboard in that you can sign up for Yahoo's program, which is likely the best thing next to Adsense for advertising programs. It's a lot easier to qualify for it (my latest site qualified in only 10 days from start-up) and the payout per click is good, too. Their TOS isn't as helplessly strict, either, so there is no need to worry about being banned from an accident or things out of your control.
Selling ad space is a good option if you can convince any local businesses and such to do so, but you will probably need a certain amount of higher traffic coming to your site to more easily sell that space, and it is much more reliable than any one ad program alone. One of my sites gets 50k visitors per month, and I've managed to sell ad space for a nice $850 per unit, which is an entire mortgage or rent payment right there. I highly suggest you consult with local businesses, even small businesses, and egg them on to buy your ad space even if you're only average a few hundred viewers per month. I would not underestimate this, because if you can manage to put things into perspective for them (provided you aren't a shy person), you can easily convince them to buy your adspace by, say, comparing how much money they spent advertising in malls or on billboards for a few hundred people to see vs. advertising on your site for a few thousand people to see.