There are no shortage of location-based services launching this week at SXSW in Austin, Texas. Many of them allow you to “check-in” places to let others know you are there. So how do you differentiate between then and decide which to use? Well, here’s one good way.

CauseWorld, is a free iPhone and Android app that lets you check-in places, but it has an added real-world bonus: big brands give money to charity when you do so. And this week at SXSW, CauseWorld is teaming up with TechCrunch to offer double point (which they aptly call “karma”) when you check in to one of over 50 venues around Austin (I’ll paste the full list at the bottom of the post), including the Austin Convention Center (where SXSW is held).

We’ve covered CauseWorld, which is the first offering from the soon-to-launch ShopKick, a few times now. It’s a great product because it takes an area that is red hot right now, location-based check-ins, and converts it into good deeds in the real world. For example, if you check-in at a store, you may earn 20 karma points. As you continue to accumulate these, you can turn them into real dollar donations for causes such as water in Sudan or trees in the Amazon. Brands such as Kraft Foods and Citi are currently giving the donations based on what users choose to trade their karma points for. The best part is, you don’t even have to buy anything — you simply check-in at various venues and earn the points. And again, this week at SXSW, checking-in with the app at a bunch of venues will earn you double karma points.

And like any good service with a gaming element, there’s a leaderboard to show who has donated the most karma points. And yes, checking-in can earn you badges, such as the TechCrunch one show in this post.

So if you’re going to be in Austin for SXSW this week. Or really, if you just want to do some good with your mobile device, check out CauseWorld. Find it in the App Store here, or in the Android Market (on your Android device).

Below find the 54 participating double karma Austin check-in spots:

1. Aces Lounge
2. Alamo Drafthouse
3. Amsterdam Café
4. Austin Convention Center
5. Austin Music Hall
6. B D Riley’s Irish Pub
7. Barbarella
8. Beso Cantina
9. Bob Bullock Theater
10. Buffalo Billiard
11. Café Mozart
12. Carver Museum and Cultural Center
13. Cedar Door
14. Chupacabra Cantina
15. Chuy’s
16. Clay Pit
17. Club Deville
18. Cuba Libre
19. Dirty Dog Bar
20. Elysium
21. Emo’s
22. Emo’s Annex
23. Flamingo Cantina
24. Hyde Park Bar & Grill
25. Iron Cactus
26. Karma Lounge
27. Kenichi
28. Kerbey Lane
29. La Zona Rosa
30. Lambert’s Downtown
31. Lustre Pearl, Lustre Pearl Bar
32. Malaga, Malaga Tapas & Bar
33. Malverde
34. Mellow Johnny’s
35. Molotov Lounge
36. Moonshine Bar and Grill
37. Opal Divines
38. Palm Door
39. Red 7
40. Red Eye Fly
41. Rudy’s Country Store and BBQ
42. Rusty Spurs
43. Salt Lick BBQ
44. Spider House Café
45. Stubb’s BBQ
46. Stubbs
47. The Belmont
48. The Best Wurst I
49. The Highball
50. The Scoot Inn
51. Uncorked Tasting Room
52. Velveeta Room
53. Victory Grill
54. Vortex Repertory