A Question: Blogs and Ads

Just a question today (it's been a long and stressful day, so I don't think I can manage more than this at the moment).  I'm contemplating becoming an 'Amazon Associate'.  I think that's what the program is called.  I've noticed a variety of book bloggers have those little Amazon boxes on their blogs and can get credit when people use that as a portal to get to the store.  I've not wanted to have any ads on my blog, though I did break down and had Brainiads on my sidebar.  I always thought of them as being sort of high-brow, and not so obviously advertising.  Unfortunately they have gone out of business.  So, do I jump on the Amazon bandwagon or keep my blog ad-free?  Is it worthwhile?  I sort of hate to just promote one internet bookstore, and I'm not exactly sure Amazon would necessarily be my first choice (I shouldn't admit that or they won't let me be an associate!), but it's hard to not be tempted by Amazon book credits.  Anyway, any thoughts?  Good, bad or otherwise?