Lucidchart is a multi-platform diagram tool. Though I only spent time with the iPad app, it is also available on the Web. It’s compatible with Visio and Onmigraffle, making it easy to use your iPad to read IT diagrams.
That professionalism might make the app a bit too complex if you’re looking to do basic mind mapping. On the other hand, there are a ton of diagram options, including custom things like Cisco network diagrams. The interface makes drawing these pretty easy, but I think the app could still use some better in app tutorials. (There are a bunch of videos on the site you can watch.)
The app is free to try, but to have more than five diagrams you’ll need to buy a subscription. You can get an invididual subscription for 5 or 6 dollars a month, depending on the length of your subscription. This is overkill if you’re looking for an outliner/mindapper, but is a good way to use your iPad in the enterprise.
What’s Good: Powerful diagram drawing, tons of custom shape templates.
What Sucks: Needs a beter tutorial, overkill for basic mindmaps.
Buy It?: If you’re looking for a way to use your iPad to read Visio or Omnigraffle docs, check out Lucidchart. Download it on the App Store for free.