Coldplay’s U.S. sales in the first week the album went on sale last June: 721,207. U2’s sales for its first week, which ended yesterday: 483,925.

What gives? I’m not a huge fan of either band, so I won’t opine about the albums’ relative merits. And the most obvious answer is that CD sales drop every year, so a big album in 2008 is be a smaller album in 2009.

But I will note that Coldplay got a huge push from Apple (AAPL) last year, which promoted the band over and over and over again on TV ads.

U2 has been working its disc very hard, too–most notably, a week-long stint on David Letterman’s CBS (CBS) show. But maybe a simple iTunes/iPod spot–like the one the band did a few years ago–could have done the trick.

Album promotion circa 2008:

To spell that argument out: Just because people aren’t paying $10 to $17 for a CD anymore doesn’t mean that people aren’t interested in music, and in some cases willing to pay for it.

Even if that’s true, it won’t do very much for the people who run big music companies like Vivendi’s (VIV) Universal Music and Warner Music Group (WMG), who are still stuck selling CDs and will be for years to come.

But nimble competitors think they can carve out a niche for themselves by working outside the labels and selling small batches of music-related stuff, if not CDs. That’s the premise of Topspin Media, a start-up headed by Ian Rogers, an entrepreneur who briefly ran the music unit of Yahoo (YHOO). Topspin sells a suite of tech tools designed to help artists (and/or their business people) who want to sell their product and manage their careers on their own.

The company is just creeping out of stealth mode, so it’s too early to tell whether Topspin’s prospects are any more or less promising than the future of the music business. But Rogers is a persuasive guy, so it’s best to just step aside and let him make his own pitch.

Here’s a slide from a recent presentation Rogers gave at a music industry event in Seattle that sums up his “people like music” argument. (Click on the image to make it bigger.) His larger case, which, of course, includes a role for Topspin, can be found here. Or if you just like slides, here.