Rosetta Code itself keeps an up-to-date alphabetical list of tasks already solved in Perl 6; you can find this in the lower section of the Rosetta Code Perl 6 category page.
Rosetta Code's category collection is weighted towards language names, tasks whose solutions where too long and had to be split onto multiple pages, and so on. To make it easier to find the tasks you're interested in, here is a shorter category list, with links directly to the Perl 6 solutions:
These tasks and solutions were nominated by members of the Perl 6 community as our favorites -- perhaps because the task fits our collective whimsy, or because the solution struck us as particularly beautiful. Here then, in no particular order, are the entries that -Ofun for us:
A 2D cellular automaton simulating fires and forest growth, with 木 trees and a touch of color for the fires.
A simple task of finding the last Friday in each month of the year, with two brief solutions: an imperative one in the style of several other dynamic languages, and an impressively short functional solution using classify and Whatever blocks.