Alarm clock xtreme: better than standard/stock alarms, more options, slow ramp up alarm capability to prevent cardiac arrest upon wakeup, lol. Can combine timer & stopwatch xtreme to be accessible from same app (aka- can hide one in hidden app drawer)
https://play.google.com/store/apps/details?id=com.alarmclock.xtreme
App installer ad free: has several functions besides the obvious. I mainly use it to make copies of a downloaded app that is embedded where I normally can't touch them (aka - no root). Free version available Small file apk
https://play.google.com/store/apps/details?id=com.funtrigger.appinstaller.adfree
Call log shortcut: Cuz JB didn't have an app for call logs, I use this. VERY small file - 30k
https://play.google.com/store/apps/details?id=se.erikofsweden.erikutil
Camera JB+: This is the camera app I replaced the stock on with (inspired by Shinru's Awesome Android) Verrry nice - includes fully editable gallery. I think there's a free version too..
https://play.google.com/store/apps/details?id=com.moblynx.camerajbplus
CoolReader: by far the best book reading app available. HIGHLY customizable and reads everything but PDFs
https://play.google.com/store/apps/details?id=org.coolreader
Jelly Bean 4.2 keyboard: free version available too. Highly customizable, way better than stock. Can even use 99% of the available keyboard themes on market.
https://play.google.com/store/apps/details?id=jellybeankeyboard.f.g.full
Keepscreen: tired of you screen blacking out but only want it to stay on with certain apps? Here ya go
https://play.google.com/store/apps/details?id=com.tni.KeepScreenLite
Kingsoft office: the best free office program with the most capabilities and no ads
https://play.google.com/store/apps/details?id=cn.wps.moffice_eng
RealCalcPlus: scientific calculator (like a Ti-36) I ALWAYS replace stock calc with. Free version available too.
https://play.google.com/store/apps/details?id=uk.co.nickfines.RealCalcPlus
SD Rescan: you ever accidentally erase something and was screaming "Noooo!"? This one saved my butt plenty of times. Just don't reboot before you use it..
https://play.google.com/store/apps/details?id=com.bero.sdrescan
Send to SD card: so dang useful I converted it to a system app. Not all SD cards or ROMs have this capability embedded so this one is a must have. I keep this one in hidden apps section)
https://play.google.com/store/apps/details?id=ru.gelin.android.sendtosd
Stopwatch xtreme: comes with timer countdown - see alarm cock xtreme. (I hide this one in hidden apps since all 3 apps can be accessed by alarm app)
https://play.google.com/store/apps/details?id=com.alarmclock.xtreme
PdaNet 3.50: USB tethering for Windows, doesn't have data limit (pre PdaNet+) and works awesome and integrates with SMS
https://play.google.com/store/apps/details?id=com.pn.helper
Tuner-gStrings (instrument): Name says it all. I've tried everyone of them and I like this one because it seems most accurate and easy to read. Quite a few options and customizable. One of my faves.
https://play.google.com/store/apps/details?id=org.cohortor.gstrings.tyd
ZArchiver: compresses to 7zip, zip, gzip, bzip, XZ, tar. Uncompresses lots more. Modify/Edit archives, extract, add. Variable compression ratio... Lots of options.
https://play.google.com/store/apps/details?id=ru.zdevs.zarchiver