The Feature requests page is a simple application for collecting feedback from actual users about what new features (or changes) should be added to DoneCal next. Due to lack of time, all feature requests can't be satisfied so with this application it becomes possible to know what matters the most and hence should be attacked first.
Anybody can suggest a new feature and doing so automatically puts your vote on it. Then, once added, you can hope that other people will vote it up too.
Voting weight is basically a count of the number of event entries you have. If you have many entries you are most likely a frequent user so your vote counts for more. To be able to vote and to add new feature requests a prerequisite is that you have created an account.