Who contributed the most? The least? Why did it take two years to raise the required sum?
Based on this question which never got much of an answer http://www.reddit.com/r/AskHistorians/comments/1vm2fq/how_much_gold_did_a_king_or_knight_usually_have/
Wow, this is a great question because if we knew the answer we'd know so much about the economy of the Angevin empire.
However, unfortunately I think the documentation is too sparse to really know the answer. From Bartlett's "New Oxford History of England: England under the Norman and Angevin Kings":
Most important, extraordinary taxation, that is, the special levies raised periodically, do not usually show up in the Pipe Rolls. It is only by luck that the figure raised by the tax on income and movable property in 1207 (a staggering £60,000 pounds) is known. The huge sums raised for Richard's ransom have left virtually no documentary trace. Special accounting arrangements were obviously made on such occasions and their records are not preserved, with the exception of a few concerning the tallage of the Jews.
(p. 159-160)
What we do know is that the ordinary land tax (danegeld) supplied only perhaps £2000-4000 pounds. The bulk of the ordinary Exchequer revenue was from the proceeds of the royal demense, and the rights of the king to receive inheritances and payments for administering justice. This all together was somewhere in the neighborhood of £24,000-35,000 in 1194.
What we know about Richard's ransom is that it was primarily raised by "a tax on movables and income" (Bartlett p. 167) at 25%. The 1207 tax (for which we have the total figure) was at only 8%, but we probably can't assume that the total collected was correspondingly smaller in 1207 due to changes in the degree of evasion and normal inflation. In any case, theoretically the people who would have contributed the most to this tax would have been those with a lot of movable property and cash income, perhaps more likely to be merchants than nobles.
The tax for Richard's ransom took so long to collect because it was a relatively new tax (prior to 1194 it had been only collected in 1166, 1185 and 1188) Fixed infrastructure was lacking. Local bishops proclaimed the tax, and then convened a sort of panel consisting of local church officials, royal officials, representatives of the local nobles and other local authorities (all along with their clerks) to decide who owed what. As you might guess, that would involve some wrangling, but it was apparently done off the books.
TL:DR Oxford history of England says there is no documentation of who paid the most or how many paid.
This isn't associated with nobles as such, but certainly to the 1192 ransom! The Jewish population of England were gathered together when news of the ransom came to England and were compelled to give money towards the ransom. This was called the Northampton Donum:
http://www.jewishvirtuallibrary.org/jsource/judaica/ejud_0002_0015_0_14915.html
A recent book, which introduces Jewish colonisation in 12th-century England, discusses the Donum (p.32), and proposes that the community gave 5,000 marks. Check p.34 for a table of the largest contributors in the Easter Term: