Part 1
http://nlvm.usu.edu/en/nav/frames_asid_160_g_4_t_1.html
Here is the link for my manipulative. It deals with percentages; the part, the whole, and the percent. I would use it with my scholars to introduce the concept of percent and how it is related to fractions and decimals. I would have them enter random numbers into each category and record their results along with a visual drawing of what appears on the computer. I would then ask them what do they think percentages are and how they are related to fractions or decimals. I would then provide them with world problems where either the percent, whole, or part was missing and have them solve them by entering the information into the manipulative program. I would improve this virtual manipulative by allowing the scholars to type word problems where they would identify the whole, part, or percent and then the information would be transfered into the appropiate boxes so that they could study the visual aspect of it. I would add marking to the fraction tile or pie graph so they can see what 25%, 10%, and other percentages look in regards to 100% of an item. I believe they should be allowed to visualize what something great than 100% looks like as well because everything isn't always out of 100%.
Part 2
I believe that algebra tiles, fraction tiles, geometrical pattern blocks, money, and a host of other manipulatives are still relevant in present times. I believe that historical "tools of the trade" provide a strong foundation which scholars can build upon (especially in their developmental stages) and it also provides historical context and frame of reference. I still use pattern blocks, algebra tiles, and fraction tiles. I use these manipulatives because it assists my scholars who have a hard time visualizing concepts and need tangible items to make sense of things. Algebra tiles have always been a great tool for me to introduce the concept of using variables or integers, especially for my low level learners. Fraction tiles bridges the gap for scholars who quite don't get the concept of equivalent fractions or what the idea of fraction is in general. Pattern blocks are great for introducing geometry. I have used them to teach the differences and similarities of each polygon, games in which they would reconstruct a picture made up of various polygons, or to show which shapes are composed of other polygons. I believe that if we stop using these historical "tools of the trade", then we will lose an important aspect of teaching mathematics.
Part 3
I would redesign graph paper as a manipulative than is both physical and computer based. I guess it would be similar to the technology used for computer tablets that allow you to draw with a stylus. The scholars would be provided with graph paper designed tablets that would in turn record there drawings on virtual graph paper on a computer or technological resouce such as an iPad or Smart Board. I would also allow the teacher to be able to pull up a scholars work on the Smart Board, projector, or computer to point out any successes or challenges the scholar may have. This would also allow scholars to save paper because they would only print out their best work, once they have mastered the concept being covered. This could also be converted into an app for people that have smart phones or touch screen devices; with the incorporation of a stylus or their finger. Some options that you could incorporate into the technological side of the device is determining the best fit line one your plot points on your graph, identifying the minimum or maximum of a parabola, or determining the x- and y-intercept coordinates. There are a host of other options that you could implement by using this idea, but these are just a few I was able to think of.