I don’t have to write things out by hand much anymore, but I can remember back in college and when I had a real job it seemed like my pen was constantly running out of ink. It sucks to have to stop what you are doing and hunt down an ink pen. The reason the ink always ran out is that the little clear tubes inside just don’t hold that much ink. You could get a much larger ink holder inside since the barrel of the average pen has a lot more room than is used.
A new ink pen concept that is very simple yet innovative is making for one of those "Why haven't they thought of that before" moments. Rather than using a straight straw to hold the ink the designer of the pen used a spiral ink tube that has greater surface area and can hold twice the ink of normal pens. That means not only will you not have to go schlepping around your home or office as often looking for a new pen, but you can be greener too.
The green feature comes in the amount of plastic that is saved from landfills when we toss those disposable pens into the trash when they are empty. The pen the fancy ink cartridge is inside is retractable to keep the tip from drying out. It looks like the fancy pen could be made cheaply too. The design is an entry for the 2011 iF concept design contest.