Plenty of inspirational tricks including screen upgrade, overclocking, installing additional internal storage and more can be found at http://www.altechnative.net/.

You can use a lightweight https://github.com/gandro/input-event-daemon, it should listen on /dev/input/event4 for LID:0 and LID:1 events.

To get maximum of the unaccelerated framebuffer driver you can use mplayer2 (it uses libraries with SMP support) and this ~/.mplayer/config

ao=alsa
mixer-channel=Master
vo=x11
zoom=1
sws=0
hardframedrop=1
lavdopts=fast=1:skiploopfilter=all

#!/bin/sh
cookies_file=`mktemp /tmp/youtube-cookies.XXXXXX`
rm $cookies_file
url="`youtube-dl --cookies=$cookies_file -g --max-quality 35 $1`"
mplayer -cookies -cookies-file $cookies_file -cache 2048 $url
rm $cookies_file

To be able to hear simultaneous playback from different programs copy this to /usr/share/alsa/cards/tegra-alc5632.conf:

# default with dmix/dsnoop
tegra-alc5632.pcm.default {
	@args [ CARD ]
	@args.CARD {
		type string
	}
	type asym
	playback.pcm {
		type plug
		slave.pcm {
			@func concat
			strings [ "dmix:CARD=" $CARD ",RATE=44100" ]
		}
	}
	capture.pcm {
		type plug
		slave.pcm {
			@func concat
			strings [ "dsnoop:CARD=" $CARD ",RATE=44100" ]
		}
	}
}

Add this to ~/.asoundrc:

pcm.softvol {
        @args [ NAME ]
        @args.NAME.type string
        type softvol
        slave.pcm "default"
        control.name $NAME
}

And use softvol:<custom name> for the ALSA device, like this: aplay -Dsoftvol:“Aplay Dedicated” testmusic.wav

You can use xkbevd to play an arbitrary sound when an XkbBell event is generated. For URvxt you need to tell it to use xkbbell for bellCommand. A better solution would be to extend input-events-daemon to create a virtual input device capable of receiving a system bell, that way it'd work equally well for all programs even without X.

• compat-wireless provides newer wireless drivers that work better but wireless extensions (only needed for some specific programs using this deprecated interface, e.g. aircrack-ng) will not be enabled until the kernel is compiled with support for some old pre-mac80211 driver (to select CONFIG_WIRELESS_EXT).
• iw dev wlan0 set power_save off to improve interactivity when a power-saving compatible AP is used

Place this in /etc/network/interfaces (on a Debian-like system) to have automatic wifi roaming controllable with wpa_cli and support for the GSM/UMTS modem:

# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

allow-hotplug wlan0
iface wlan0 inet manual
        wpa-driver nl80211
        wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

iface default inet dhcp

iface home inet dhcp

iface wwan0 inet dhcp
        pre-up stty -F /dev/ttyACM1 1:0:80001cb2:0:3:1c:7f:15:4:5:1:0:11:13:1a:0:12:f:17:16:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0 2> /dev/null || \
               stty -F /dev/ttyACM1 1:0:80001cb2:0:3:1c:7f:15:4:5:1:0:11:13:1a:0:12:f:17:16:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0
        pre-up chat -v TIMEOUT 30 ""                                    \
                        AT OK                                           \
                        AT+CGREG=1 OK                                   \
                        AT+CFUN=1 "+CGREG: 1"-AT+CFUN=1-"+CGREG: 1"     \
                        "" ABORT ERROR ""                               \
                        AT*ENAPDBG=1 OK                                 \
                        "AT*ENAP=1,1" "*ENAPDBG: 1,1"-"AT*ENAP=1,1"-"*ENAPDBG: 1,1" < /dev/ttyACM1 > /dev/ttyACM1 || \
                                 ! chat -v "" AT*E2RESET < /dev/ttyACM1 > /dev/ttyACM1
        post-down chat -v "" AT+CFUN=4 OK < /dev/ttyACM1 > /dev/ttyACM1

This assumes your card has PIN disabled, if it's not, you should be able to add AT+CPIN=“abcde” command where appropriate. If you hot-swap the SIM card you might need to issue the AT*E2RESET command manually. The modem supports messaging via SMS and USSD requests, e.g. this works with Beeline to see the amount of money left:

#!/bin/sh
/usr/sbin/chat -vs "" "AT+CUSD=1,\"*102#\",15" "OK" < /dev/ttyACM1 > /dev/ttyACM1