For phone usability, i'm using:
billboard - configurable lowpowerscreen
autolock_1.0.1_armel.deb - lock when proximity sensor is covered
callrecorder_0.0.9_armel.deb
clipbookdir_3.0.0_armel.deb - manage clipboard better
connectedvibro_1.2.0_Nokia-Love.ru.deb - though it is not the best, as caller can hear your vibration beeping.
firewallpluspro_1.5.1_armel.deb - sms and call blocking, i have not used yet, just tested, this don't make any sound when blocked number is calling, another app 'callblocker' was ringing once
hmtsu_0.2.2_armel.deb - if i want to launch an app as root
keeppageplugin_1.0.0_armel.deb - remembers last displayed page in stock pdf viewer
oobtodo_0.0.1_armel.deb - just a quicklink to stock 'todo' user interface

opptimizer_1.5.4_armel.deb
opptimizer-ui_1.2.7_armel.deb - dangerous game of overclocking a cpu, i'm running my n9 @1100MHz, 1150MHz also ran stable without any voltage changes, i preferred to be conservative.

fastern9 - i'm using stable 1.01 version of this performance tweak

organiserfeed_1.1.80_armel.deb - can display stock todos and calendar events at the feeds screen, few limitations, but i prefer this to 'calendarfeed'
profilematic_2.5.0_armel.deb - for phone tasks automation, i think this is must have app
speakerswitcher_2.0.0_armel.deb - for switching speaker on or off upon proximity, though i have heard complaints that speaker produces echos on the other side.

n9-qtweakall_9.8.8_armel.deb - i'm using this a lot (root passwd must be unchanged (if i'm not mistaken)), has the power to mess up everything



Apps, and why:
exnote_1.3.1_armel.deb - this saves notes as separate html files, easy to backup, no cloud. I prefer it over stock Notes app.

I have found that cuteradio still plays at least somafm radios, and, also, cutesoma still works. Also, there's streamripper cli app which can record online radios, it has a dependency issue, but works, deb could probably be just unpacked and binary dropped to /usr/local/bin if aegis-apt-get complains too much.

quickcurrency - an only working currency app there is
josemobile - beat your n9 in chess

Audio players:
rplay - lightweight directorybased audioplayer
abplayer - audiobook player
quasarmxfull - full version can probably still be bought from meteorasoftworks.com

meeftpserver_1.0.4_armel.deb - for file transfer between devices, there's also good http server app 'wifitrans', and 'sshfs' for connecting a folder from or to pc (cli program).

Here are most apps (and games) i'm keeping installed currently.
https://drive.google.com/drive/folde...wH?usp=sharing

Edit: I have painted red the apps which are potentially dangerous to meddle with, if your phone works ok for you, and if you have never flashed any firmware and don't know how, then probably better not use these. I have had to reflash my n9 multiple times because of different reasons.

Edit2: There are proper procedure to install system apps, either from terminal using aegis-dpkg or using debinstall app with "Trusted" tickmark ticked and tapping on Dpkg button. Debinstall itself has to be installed from terminal (aegis-dpkg -i). All info is here in the forum, but i just realized that, for a rookie, some of the apps could be explosives.

Edit3: I'm installing most apps using debinstalls Trusted/Dpkg method, because then i don't have to adjust my phones date/year. Also, i consider Fastern9 generally safe, but it has to be installed with privileged cli or debinstall method or through n9qtweak. Here, since i had nothing else to do, i made screenshots from each n9qtweak tweaks for better reference.