yes! You can monetize your free blog any way you want to. Becoming an affiliate for a product you use or simply want to recommend - is also another good way to make money from your Blog's traffic. You can put Banners and other Ads on the side, on top and at the bottom of your page. Anywayss.... I wish you the best success in your journey online! ...
It's very ironic and maybe a little biased on Blogger's part to prevent a blog user from selling ad space, considering how they push Adsense on the blogger as if that is the only advertising option. And, while I think Adsense can play a good part in earning money on a very active, high traffic blog, it's not the only option for bloggers who want to earn a full time income. Joint ventures, endorsing affiliate products and selling your own products give better commissions than putting up Adsense, especially for the new blogger who is not likely to sell much ad space anyway or who doesn't have the traffic for good Adsense earnings.