A study conducted by app store analytics company Distimo has reveled that on average, apps hosted by the Windows 7 Phone Marketplace are cheaper than apps hosted by Apple’s App store, Google’s Android Market, BlackBerry’s App World, Nokia’s Ovi Store, and Palm’s App Catalog. The study revealed that on average, apps hosted by the Windows 7 Phone Marketplace cost $1.95, half as much as app hosted by Apple’s App Store, which cost on average $4.

There’s one other thing the Distimo report brought to light – the most popular free apps hosted by the most popular app stores out there. So if you are curious to see which are the most popular free apps hosted by Apple’s App store, Google’s Android Market, BlackBerry’s App World, Nokia’s Ovi Store, Palm’s App Catalog, and Microsoft’s Windows Phone 7 Marketplace, take a look below.

Top 10 Most Popular Free App Store Apps (for iPad)

1. Nightstand Central for iPad Free
2. Cut the Rope HD Lite
3. iBooks
4. TED
5. NYTimes for iPad
6. ScoreCenter XL
7. Calculator for the iPad+
8. The Weather Channel Max for iPad
9. Netflix
10. Victoria’s Secret

Top 10 Most Popular Free App Store Apps (for iPhone)

1. Cut the Rope Lite
2. 0.03 seconds
3. Catapult Madness
4. Glow Background IN ONE
5. Rat on a Scotter XL
6. Ringtone Maker
7. Trainyard Express
8. Tesla Toy
9. The Moron Test: Section 1
10. Facebook

Top 10 Most Popular Free Android Market Apps

1. Pandora Radio
2. Google Maps
3. Advanced Task Killer
4. Facebook for Android
5. T-Mobile My Account
6. The Weather Channel
7. Barcode Scanner
8. Google Sky Map
9. Talking Tom Cat Free
10. Kakao Talk

Top 10 Most Popular Free BlackBerry App World Apps

1. BlackBerry Messenger
2. Poynt
3. Pandora
4. crunchSMS
5. Facebook
6. FREE Sea Storm Animated Theme
7. Twitter
8. ScoreMobile for BlackBerry
9. Windows Live Messenger
10. PrivacyStar

Top 10 Most Popular Free Windows Phone 7 Marketplace Apps

1. YouTube
2. Xbox LIVE Extras
3. Facebook
4. Adobe Reader
5. Netflix
6. Shazam
7. Twitter
8. Unite
9. The Weather Channel
10. IMDb Movies, TV, & Celebrities

Top 10 Most Popular Free Nokia Ovi Store Apps

1. FingerPrint Scanner
2. FindMe
3. SlideUnlock
4. Marble Maze Classic
5. Screen Crack Prank
6. Skiller WallBall
7. Nuke Defender
8. Horn Attack Lite
9. airPainter
10. Road to Hell 3D

Top 10 Most Popular Free Pall App Catalog Apps

1. Facebook
2. pRingtones
3. TuneIn by RadioTime
4. Pandora Radio
5. RednecksVs.Aliens (Pre& Pixi)
6. SuperJump (Pre& Pixi)
7. Fantastic Wallpaper
8. Putki(Insanely addictive 3D tunnel game)
9. Bubbles! Free
10. Ground Effect

Please note that the top 10s presented above apply to the month of October, 2010. The App Store and Android Market top 10s were based on US app popularity; the other tops were based on international app popularity.

You can download Distimo’s report here.