This app was mentioned in 11 comments, with an average of 3.91 upvotes
I think you mean /u/JeepinJon not /u/accents but I forgive you ;)
Edit: And thank you for the shout out! I'm working hard to get Ofcom (UK) to share their data, which they said they would do but it's been somewhat slow going. We've recently added Grid Squares as well. US Amateur Radio Band Plan for Android has added a callsign lookup feature to their app that is powered by HamDB.org's API, so we've made it into one app that I know of so far!
In addition to the ones previously mentioned, check out:
* US Amateur Radio Band Plan
* RepeaterBook
Both are excellent.
Just get your Extra so you don't have to remember what you have access to :)
But seriously, I second the US Band Plan App for Android. I think the author is also on this sub and is receptive to feedback.
I also keep a pdf of the Graphical Frequency Allocations chart on my phone, just in case.
If you have a premium subscription to radioreference.com, you can run reports and download pdf's or csv's for all manner of systems and frequencies.
I really like "US Amateur Band Pland" for Android:
https://play.google.com/store/apps/details?id=com.kimbrelk.ham
It includes a bunch of non-amateur frequencies like CB, maritime, NIST, MURS as well. It has ads, but those can be removed with an in-app purchase - I think I paid around $2-3.
If you have an Android device, my friend's free band plan app is a good reference.
You can memorize it using the ARRL's band plan chart or this free Android app.
You can also compute the wavelength or frequency using that super simple formula. Use the 300 for a rough appromomation of the speed of light, and your answer will be in Mhz. (common for amateur radio bands)
(I may have forgotten some. Will update.)
US Amateur Radio Band Plan - Simple, lightweight, and clean, free app by my friend, KA4SON. Also includes some non-ham info, too. - FREE / optional $0.99 premium upgrade.
RepeaterBook - Location-aware repeater info app. - FREE
Antenna Tool - Simple Antenna length calculator - FREE
Coil32 - Inductance coil calculator - FREE
APRSdroid - Well-rounded full featured APRS client with Bluetooth support. - $4.95
Ham Radio Call - ULS Lookup with built-in map upon lookup. - FREE
Morse Toad - Excellent Koch-based Morse learning tool. - FREE
SDR Touch - RTL (and other) SDR client for Andriod - FREE / $9.99
Solar data & HF propagation - Includes widget support - FREE
SOTA Spotter - Like a DX spotter, but for SOTA - FREE
SSTV Encoder - Self explanatory. - FREE
Robot36 - SSTV Image Decoder - Self explanatory. - FREE
DroidRTTY - RTTY App. - $5.49
Satellite AR - excelllent Augmented reality Sat-track app. - FREE
Echolink - Echolink: VOIP mixed with real RF. - FREE
KX3 Companion FREE Ham Radio - KX3 Control Front-End - FREE
Ham Radio Log - Basic Log App - FREE
Not an app per se, but: HamStudy.org - Excellent radio study and practice-test tool by /u/taxilian . Formats well on mobile. - FREE
If you have an Android device you should add my friend's app to your list. :)
That really is a great chart, and my radio club has it hanging up.
Though if you just want to see the amateur radio band allocations (USA), take a look at this chart, or my friend's free band plan app.
As for your lack of confidence in avoiding interfering with other users,
Take a look at the ARRL's band plan information.
The info in the Graphical Frequency Allocation chart is legally binding, but the extra granularity of the ARRL's band plan (link above) is a generally accepted "gentleman's agreement" that we hams try to abide by for the good of everyone to avoid what you were worried about.
My friend's band plan app has that information built in too, for a slightly easier reference.