Some may have heard or used one of the "killer-apps" for Iphone, Ballistic, http://ballistic.zdziarski.com/ or BulletFlight, http://www.knightarmco.com/bulletflight/index.htm . I personally feel a need for a one, and I presume that there are users out there who also might benefit from this kind of an utility. There are free-ware ones floating around a lot, but sadly sources are often not included, and no pure linux variant which is useful to anything is around so a pure conversion might not be possible.
please include that this tool should be for snipers and people who do ranged shooting within your proposal.