Creating backlinks are important. There are different type of backlinks. Besides of high pr domain backlinks, .org and .edu backlinks are worth way more than regular .com or .net backlinks. Because they tend to have more authority, Google like those type of backlinks. Following are all .org sites that you can create backlinks from, and most of them will give you dofollow backlinks.
It is important to know that when creating those backlinks, do not just make it as thought you go to their sites is simply for creating the profile and put your domain there. Do read few of the posts, and leave intelligent comments. This will give moderator the impression that you are not those spammers. Especially when you are on your niche forum, try to bookmark them, visit them frequently and reply to few posts.
Anyway, following are over 100 websites that you can build backlinks from; they are all PR5 + and all .org websites . Some of them might disable website fields, but most of them should still work. Enjoy and blast away!

1	drupal.org/forum	pr9
2	bbpress.org/	pr8
3	moodle.org	pr8
4	bbpress.org/‎	pr8
5	wordpress.org/support/	pr8
6	simplemachines.org	pr8
7	simplemachines.org	pr8
8	edge.org	pr8
9	forums.freebsd.org/	pr7
10	oecd.org/forum	pr7
11	forum.videolan.org	pr7
12	westeros.org	pr7
13	openoffice.org/support	pr7
14	mozilla.org/about/forums/	pr7
15	idpf.org	pr7
16	j-pouch.org/groupee/forums	pr7
17	forums.egullet.org	pr7
18	alzforum.org	pr7
19	caringforclimate.org/forum	pr7
20	ipv6forum.com	pr7
21	freeforums.org	pr7
22	youthforum.org	pr7
23	buddypress.org/support	pr7
24	budapestopenaccessinitiative.org/forum	pr7
25
26	forum.joomla.org	pr6
27	bitcointalk.org	pr6
28	stormfront.org	pr6
29	stormfront.org/forum	pr6
30	eclipse.org/forums	pr6
31	ubuntuforums.org	pr6
32	adblockplus.org/forum/	pr6
33	broadband-forum.org/‎	pr6
34	broadband-forum.org	pr6
35	forum.audacityteam.org	pr6
36	linuxquestions.org	pr6
37	forumforthefuture.org	pr6
38	dailystrength.org	pr6
39	silverstripe.org/forums	pr6
40	tmforum.org	pr6
41	skollworldforum.org	pr6
42	youthforum.idebate.org	pr6
43	asq.org/	pr6
44	sciencemag.org	pr6
45	forum.cmsmadesimple.org	pr6
46	uefi.org	pr6
47	fortefoundation.org/site	pr6
48	mmfai.org	pr6
49	mudcat.org	pr6
50	forums.zotero.org/6	pr6
51	igem.org/Forum	pr6
52	blender.org/forum	pr6
53	summitpost.org	pr6
54	medhelp.org	pr6
55	ashraexchange.org	pr6
56	ifg.org	pr6
57	stakeholderforum.org	pr6
58	schizophreniaforum.org	pr6
59	limesurvey.org/en/forum	pr6
60	immigrationforum.org	pr6
61	fedoraforum.org	pr6
62	edctpforum.org	pr6
63	wapforum.org	pr6
64	tt-rss.org/forum	pr6
65	apug.org	pr5
66	vbulletin.thesite.org/	pr5
67	websitebaker.org/forum	pr5
68	vbulletin.org/forum	pr5
69	blenderartists.org	pr5
70	conceptart.org/forums	pr5
71	forum.doom9.org	pr5
72	usa-flag-site.org/forum	pr5
73	hydrogenaudio.org/forums/	pr5
74	forum.winehq.org	pr5
75	webpagetest.org/forums	pr5
76	worldheritagesite.org/forums	pr5
77	head-fi.org	pr5
78	cyburbia.org/forums	pr5
79	forum.m1911.org	pr5
80	webpagetest.org/forums	pr5
81	worldheritagesite.org/forums	pr5
82	head-fi.org/	pr5
83	phidot.org/forum	pr5
84	forum.civicrm.org	pr5
85	forums.cgsociety.org	pr5
86	holcimfoundation.org/Forum	pr5
87	raspberrypi.org/forum	pr5
88	celinuxforum.org/	pr5
89	preservationnation.org/forum	pr5
90	sites.ieee.org/wf-iot	pr5
91	car-seat.org	pr5
92	rosettacommons.org/forum‎	pr5
93	skollworldforum.org	pr5
94	endometriosis.org	pr5
95	freesound.org/forum	pr5
96	techguy.org/	pr5
97	forums.llli.org/‎	pr5
98	wandisco.com/svnforum/‎	pr5
99	our.umbraco.org	pr5
100	sigir.org/forum/	pr5
101	sawmillcreek.org	pr5
102	craftster.org/forum	pr5
103	forums.opensuse.org	pr5
104	fudforum.org	pr5
105	meforum.org	pr5
106	tvtropes.org/pmwiki/topics.php	pr5
107	hdmi.org	pr5
108	mindat.org/forum.php	pr5
109	ccmixter.org/forums	pr5
110	linuxfr.org/forums	pr5
111	oooforum.org/‎	pr5
112	uselectionatlas.org/FORUM	pr5
113	qt-project.org/forums	pr5
114	poets.org/poetsforum	pr5
115	occupywallst.org/forum	pr5
116	tiki.org/forums‎	pr5
117	forum.3ders.org	pr5
118	ccel.org/forum	pr5
119	icap-forum.org/	pr5
120	alljoyn.org/forum‎	pr5
121	ubercart.org/forum	pr5
122	recovery.org/forums	pr5
123	answers.opencv.org	pr5
124	alz.org/forum	pr5
125	forum.suprbay.org	pr5
126	forum.ubuntu-fr.org	pr5