Personally, I feel filling forms are never fun, We can just make it less boring with some techniques. As far as,the fun element is concerned, they can always be added through visual aids. Our mind fundamentally is more of a visual tool than that of a Textual tool. Even the fun elements can be added as part of design, here are some suggestions:Lets reduce the Cognitive load with adding simple interaction elements like Buttons, sliders, drop down menu. The idea is to include the natural human tendency to act in a certain way. A lot of animations and Jquery can actually make the form unusable.The Visual Load can be reduced with keeping the basic eye movements under consideration while designing the fields. In below image we can see how designing form in certain way can lower visual load. The Motor load can be diminished with the use of larger intuitive buttons.I am writing down some of the ideas that I know with which we can make Form Filling Less cumbersome if not playful or fun, You may add in comments too.The idea is create Engagement/Interactions not forms. E.g. Take for example Tripit. This application for managing your travel plans by using your travel confirmation emails could easily have asked all new members to sign up through a registration form. Instead, to the join the service new members simply have to send Tripit a travel confirmation email. From this email, Tripit creates an account and extracts the information it needs to create a rich travel plan for new members. No form required. People sign up for Tripit by using it and learning what the application can do for them.A different type of Sign Up form Minimize the Key Inputs, try to make it point and click for web and Touch oriented for Mobiles.Using Web Services for Login : Web services allow people to log-in to a new service using their profile and contact information from other Web sites. The idea here is to make use of information people have already provided elsewhere instead of having them fill it all in again on your sign-up form.Other Communication Tools like Email. Tripit already uses it, Posterous, which is a blogging service, let you write a blog post in your email, attach a photo, send it over to Posterous, and they'll essentially publish that whole thing for you, no need to ever get out of your email client. The idea is that input can come from anywhere. You can use your email client to provide input. You can use your IM client to provide input. You can use Twitter, or you can use your calendar. You can use book marklets or browser extensions. Mad Libs forms ask people the same questions found in typical sign-up forms in a narrative format. They present input fields to people as blanks within sentences. Create Data Extractions points at various points of user interaction. Asking people for information once they are already using an application is often more successful than asking them before they start using the application. These days linkedin.com is trying to do the same.