There is a list here: http://proxy.org/cgi_proxies.shtml
If they block myspace, etc, they might block this site too, and proxies...however, here are a few proxies from the "master list" on proxy.org you could try.
1. proxify.com (24,408)
2. proxeasy.com (18,212)
3. tunneldirect.com (17,055)
4. sslunblock.com (16,127)
5. proxylicious.net (15,561)
6. twolulu.com (15,475)
7. accessfast.info (14,711)
8. simplein.info (14,211)
9. dtunnel.com (13,255)
10. virtual-browser.com (6,302)
11. wiiproxy.com (5,996)
12. blewpass.com (5,826)
13. anyfool.com (5,742)
14. skooproxy.com (5,733)
15. buzzprox.com (5,719)
16. proxy.tc (5,351)
17. urpal.net (5,039)
18. totalnetprivacy.com (4,916)
19. freeproxyserver.eu (3,329)
20. 4proxy.de (3,068)
21. s-proxy.com (2,570)
22. heeky.com (2,248)
23. anonsafe.com (2,240)
24. myspaceproxy.nu (2,224)
25. surfease.com (2,223)
26. faqtup.com (2,174)
27. proxify.net (2,154)
28. trycatchme.com (1,923)
29. shockedmoose.com (1,807)
30. unblockbook.biz (1,807)