Tracker URL: Libble.me
Open Signups?: Quite often, there's also an invite system
Number of Users: ~ 6200
Number of Torrents: ~ 15400
You must be free of warnings to transcend user classes.
This system is currently being tested out, and it may be subject to further changes in the future. But for now:
users: Top 2%,
users: Top 4%,
users: Top 7%,
users: Top 15%.
: Special people selected by the staff, such as Subscribers, they receive unlimited invites.
: Staff at another tracker, generally approved by a staff member.
Promotions will be done twice per month, and you'll be able go down as well as up!
Every month, on the 8th, each Bronze member gets one invite (max of 1).
Every month, on the 8th and the 22nd, each Silver, Gold and Platinum member gets one invite.
Silver members have a maximum of 2 invites, Gold 3 invites and Platinum 4.
There is a hard maximum of 10 invites for all classes, that cannot be exceeded by bonus invites.
Libble is a music tracker. They initially had some sort of TBdev frontend, but switched to Gazelle by mid-2008. An interesting feature is that they don't keep track of your global ratio, but have a "Share Rank" system to make sure "everyone contributes back to the site". Your rank is increased by uploading, snatching and seeding torrents, and decreased by hit & running, for example. If your rank drops below -20, you're instantly banned.
About their content, they have a lot of torrents and some exclusive Mixtapes, which are freeleech - but otherwise aren't at the bigger music trackers' levels, in my opinion. Retention isn't the best (probably due to the ratio-free scheme), they're missing a lot of popular stuff, and according the stats, only one third of their userbase seems to be actually active on the site.
Bronze users and above get access to the "Invites" subforum, where unlimited What.cd and XTC offers can be found, as well as many other trackers users share invites to (IPT, PTM, Waffles, PTPC, and other mid-low level sites). You need to be a Silver user or above to qualify for a What invite. You may have a hard time advancing from User to Bronze in the beginning, since apart from being among the top 15% users on the site, it appears you must also have a certain amount of "experience" points. Experience is visible in your profile page, and is gained by posting on the forums (1p./post), commenting on torrents (1p./comment), requesting (no idea of what the experience gain is here), and snatching torrents (1p./snatch). Longevity also grants you experience, one point per month you've been registered.
If you have more information, feel free to post it.