So, you've played Minecraft for a while, and now you don't have anything else to do? NONSENSE! Theres always new things to do, like

• Start a creative world on superflat. Use character sprites from http://spriters-resource.com/ or any other resource to create Pixel Art. When I started, I didn't really know what to do, so start with something easy, like a Goomba from Super Mario Bros. Check out some of mine at http://www.planetminecraft.com/project/pixelate-1289584/
  
• Build something epic in survival! I haven't gotten around to building something too cool yet, but it seems kinda straightforward. Mine tons of stone and coal, then smelt all the cobble into stone and make it into stone bricks. I would avoid building a completely rectangular building. Try a cathedral shape, or rounding off the edges some for a more professional look.
  
• Trap a mob? You could trap them in a hole, or somehow encase them in glass. Then you could have your own little mob zoo! "WARNING: trapping mobs, especially Creepers, could get you killed! Attempt at your own risk!
  
• If you've never tried a multiplayer server, well, you've been living under a rock! Get to it...or start your own and play with friends. It's fun to play with other people, plus, you can find new ways to kill people with redstone traps, lava, etc. >:D --Try RPGuilds. It's an awesome roleplay server! I have a blog post about it and the IP is RPGuilds.nn.pe:25575--
  
• Write a book! First, craft a Book with leather and some paper. Then, you make it a Book and Quill by crafting with the Book, a Feather, and an Inc Sac. Write up to 50 pages, at 256 character's per page. Copy and paste this with Ctrl+V (on PC): §0 It is the formatting code for black and allows indents and line skips by typing spaces or hitting enter after pasting. Write an epic novel or journal! You can share it with others after signing the book, or keep it for yourself! (once a book is signed, it cannot be edited)
  
• Download a popular map from PMC, explore it and see what you can do to give it your own personal touch
  

There's lots of cool things to do in Minecraft, and if I left anything out you want me to mention, leave me a comment and I'll either add it or hope people see it in the comments. If you like the suggestions, give me a diamond or something. If you don't like it... I wanna hear that... but say it nicely please!