The 21 picks assembled here - on a playlist that can be burned onto one CD - are contenders for the songs of summer '08, tunes that may worm their way into your consciousness, if they haven't made it there already.

Some are already hits on radio, Internet or TV. One of them is 40 summers old - but thanks to McDonald's and its marketing plans for the Olympics, it will soon be inextricably linked with U.S. swimmer Michael Phelps and Happy Meals.

So, with apologies to the contenders that didn't make the cut - Los Campesinos!'s "You! Me! Dancing!", Missy Elliot's "Best, Best," and Dengue Fever's "Tiger Phone Card" - on to the list.

1. "Mercy," Duffy.

"Yeah, yeah, yeah!" Welshwoman Aimee Ann Duffy's calling card, off of her impressive debut Rockferry, is an international hit with good reason, as it sashays down the '60s soul-pop avenue with finger-snapping panache. She'll be at the Theatre of Living Arts on Aug. 6.

2. "Constructive Summer," The Hold Steady.

While his Brooklyn bar-band mates rock out, Springsteenesque storyteller Craig Finn dedicates a faithless promise - "We're gonna build something this summer" - to "St. Joe Strummer." From Stay Positive, on iTunes now and in stores July 15.

3. "Oxford Comma," Vampire Weekend.

There's been so much hype and backlash about Ezra Koenig's Ivy League foursome that it's been easy to forget what sets them apart in the first place: A knack for writing deceptively simple indie-rock songs. Their new single shows that even English grammar can be the stuff of breezy summer pop.

4. "Lollipop," Lil Wayne featuring Static Major.

No offense to Katy Perry or Coldplay, but the summer belongs to Lil Wayne. The at-once crude and inviting "Lollipop" is only the most mainstream of his current offerings. The dreadlocked New Orleanian is also garnering airplay with Tha Carter III's stuttering "A Milli" and his guest rap on Usher's "Love in This Club" remix. It's Weezy's world, we just live in it.

5. "Lolli Lolli (Pop That Body)," Three 6 Mafia featuring Project Pat, Young D and SuperPower.

Taken with Mika's "Lollipop" and the aforementioned Lil Wayne megahit, it seems that this Oscar-winning rap group is part of the season's pop-music oral fixation. T6M also uses a politically savvy ploy to get a potential paramour to disrobe: "Like Barack Obama said, it's time for a change."