Mind-mapping has really taken off as a brainstorming and planning strategy.  After you've played around with a decent mind-mapping software, you'll quickly understand why: it does simplify a whole lot of the thinking we do.  MindNode for iPhone, a mobile version of a popular genre software for the Mac, is designed to help you accomplish that while out of the desk.

While I have stored mind maps I made from a computer to my iPhone (in image format) before, I've never really tried doing much actual mind-mapping on an iPhone.  After using this a while, I remembered why.  That screen is so dang small, it's a frustrating experience (for me, at least).

If you can get over the size, MindNode works well enough as a mind-mapping tool.  Operation is simple tap-and-type (tap a node, tap the plus sign to add a child and type the label), so building a simple map is easy.  The UI is clean and largely uncluttered, as well, which is a necessity for working with mind maps on a display this small.

There's support for some advanced functions like rearranging nodes, multiple main nodes, an outline view and one-way Dropbox integration.  As a whole, though, functionality is very limited, especially if you're used to working with MindNode Pro on the Mac.  If you're planning to edit files made from the desktop version, realize that a lot of attributes won't transfer well and some won't even transfer at all (they'll disappear once you open them on the app).

At $5.99, MindNode isn't a cheap download.  While that's not that big of a problem, the limited features, most of which you'll find on free mind map apps, are a definite downside.  Probably best wait for further updates in case they're planning to beef up the feature set.

[iTunes]

Mindjet's desktop app is one of the richest, most powerful mind-mapping tools I've seen.  Their mobile effort, Mindjet for iPhone, isn't half bad, squeezing a healthy dose of capabilities and excellent usability that should satisfy most professional users.

There's nothing complicated about what it does: the app lets you perform various operations for your mind maps. The big deal here is, you've got it on your phone, so inspiration can strike anywhere and you can immediately put it down without skipping a beat.

Upon opening, it takes you a map management screen, where you can create, edit and rearrange maps (up to 100x the handset's screen size) stored on your iPhone.  Creating and editing is very intuitive - double-taps on any level lets you edit the node, change various properties (like shape and color) and add a variety of details (including remarks, dates and completion percentages).  It works exactly how you'd expect it to on a small, multi-touch display, which is fantastic.

Uploading and downloading of maps to your computer is also possible, although this led to some amount of confusion on my part.  The process is not straightforward, requiring you to go through a web service to be able to share files between your devices.  If you encounter an error, make sure to check that files have an OPML extension (not XML).  Simple renaming works.

Overall, Mindjet for iPhone is a very useful mind-mapping application (with a look similar to iThoughts).  It's nowhere near as robust as the desktop counterpart, but for simple creation and editing needs, this is great.  Pricing is a little over the top, though, at $7.99.

[Mindjet]