Instead of a regular once-monthly event like a Winter League, the Ladder League's premise's are flexibility, distributed organisation & self-regulation.
Clubs organise their own 'events' which can run on any day, and hold any number of teams - usually between 3 and 6, including the hosts & second teams. Daylight permitting, Wednesday afternoon is a very common time for Ladder League fixtures, as most universities have the afternoon off. Teams can travel to each other, start their games at around 2pm or earlier, depending on the light, and play ~3 matches in the afternoon before heading to the pub. Traditionally, teams then compete head-to-head in a three pint challenge competition to achieve the fastest time, hoping to salvage a consulation victory from any losses incurred on the playing field.
Weekend "Winter League" style events also happen, where a tournament-like schedule can be played out, more games can be played, and more time can be spent in the pub afterwards.
The results of the games are sent to your regional coordinator, or the regional volunteer running the league, or Felix, who puts them into a formula and updates the table for all to see. You will find the scoring system greatly rewards any kind of activity within the league - playing more games will get you more points. See below.
At the end of the season, a bunch of prizes donated by participating teams are given out to the top finishers & voted spirit winners. These prizes are usually club discs or t-shirts which the clubs have donated to the prize fund.

Essentially, the rules are decided by the event organiser present or by agreement between the two teams playing, but there are a number of Ladder League guidlines you need to adhere to:

• Outdoors only.
• 5/2 man/woman split encouraged - discuss it with your opponents, but wherever possible, try to have at least two women on your line.
• One non-student 'guest', usually a coach, is allowed to play for each team, providing both captains agree before the match.
• A first team and a second team from the same club are allowed to play each other, providing they are at an event with other teams present.
• Teams are allowed to play a maximum of two matches against the exact same opponents per week.
• A second team can be playing two matches at the same time - if you have enough players for a third team, their results count towards your second team on the league table. When these second & third teams play against each other, the results do not count towards the league table. A club cannot field two first teams at the same time.
• It is up to the club captain to decide whether his/her competing side at any event represents the clubs first or second team on the table, and their opponents should be notified of this before the match begins. There are no restrictions on player movements between these sides, but captains are encouraged to label their team appropriately. Note that in almost all cases it is favorable to play as your first team, because you only stand to gain ranking points by playing matches, thus there is no risk of losing any table position you wouldn't lose otherwise.
• At the start of the season, the final table positions from the last year are directly used for seeding, with the ranking points of the top team are set at 1360, the second team 1330, third team 1300, and so on for all the teams in the top half of the table, with 15 points separating the teams in bottom half of the table. If a new team joins mid-season, they are placed at the bottom of the top half of the table, and given the appropriate ranking.
• Games should last at least 30 minutes, but the exact length, cap rules, timeouts, half time, and any other debatable rules, are decided either by the captains before a match, or by the event organiser present. Callahan scores are allowed.

To encourage activity within the league, teams accumulate ranking points for every score they get. If the score is against a team with a higher rank, more ranking points are awarded, and less if it is against a lower ranked team. This way, a game between the strongest and weakest teams in the region won't award the strongest team many ranking points, but every score the weaker teams gets will assist them greatly in the table.
A bonus is awarded to the winning team, and a home/away multiplier encourages & rewards teams for travelling to another university to play.
For a more detailed explanation, see the scoring page. The formulas used try to strike a fair balance between activity and performance - good performaces against strong teams are rewarded, but high activity of clubs is of utmost importance, so you rarely see a game played where one team will not improve their ranking.

It is up to the discretion of the Uni Ultimate Committee or the Regional Coordinator as to whether, and to what extent, results from the Ladder League will be used to aid seeding of Outdoor Regional Qualifiers. It is understood by everyone that the ranking table is just as much an indication of a club's activity as it is of their performance, so should not be directly used for seeding purposes.

If you're up for some games, you have to organise them yourself. This is in fact very easy - the best approach is to announce to your regional mailing list, or to the club captains in your region, that you will be hosting a Ladder League event on [insert a date/time when you'd normally be practicing here] at [insert your practice location here], and it's open to anybody who wants to come and play against you & each other. Teams will thank you for all the hard work you've put in to organise it, and send all their players in two or three teams to play against you - so make sure you have some cones / shoes to mark out a pitch when they arrive. You might want to draw up a quick schedule & summary of the rules so people know who they're playing first and how long the games will be - check out these simple examples by Mohawks and Brunel.
If you see anyone else announce a fixture, don't miss out on the action and let the other teams in your region start pulling away from you on the table, just email your first team and your beginners asking who's up for missing a lecture on Wednesday morning, or forfeiting their usual Sunday lunch, to get to the venue on time, and you'll find your players are simply itching to play. So, get out there and play some ultimate already!