Well when it comes to writing, I use the google adwords keyword tool. It's an awesome feature for helping choose my keywords. Not sure how successful I have been with it yet but I like to think it does some good.
Hubpages is kind of like a program. Love jumping on here to write something new and check up on the fantastic writers that I follow!
Slacker radio is by far the most utilized app on the iphone that I use. Many times while out kayaking i'll turn it on and play some good old country music while drifting down stream. Love it!
The geocaching app is probably my second favorite. It has a small fee for the full version but the basic is free. It's a great way to get kids involved in geocaching. I would highly recommend it to anyone!
I am not sure if those are the exact ideas your looking for, but it may help you in some way. Good luck bud!
If I have to pick one, I would go for "Always on Top Maker". It's a tiny program that runs in the background that allows you to set a window to the top. It's great when you have to refer to one program while inputting into another.
I actually did a hub on this a while back listing Open Office, GIMP, Programmers File Editor, Guyla's Navigator and Always on Top Maker as my favorite programs:
Mozilla Firefox (my main browser). Mozilla Thunderbird (my first and only email client). IrfanView for image viewing, resizing etc. VLC player for any video formats. It plays everything without relying on system codecs. So I don't have any installed. Media Player Classic Home Cinema - my second favorite player. It handles hardware video acceleration better than VLC. IMGBurn - the only burning tool I use to create CD's, DVD's, images, unpack .ISO images and lots more.
For editing and working with images, Gimp and ImageMagick are essential for me. They work on Windows, UNIX, and Linux, and almost certainly other systems. For working with videos in any format, mplayer is hands-down the best, though it's not easy to install from source code.