If you are root of your system, you can use the audit kernel feature to have the maximum information about who/when/what accessed/created/modified files. see this tutorial for debian-flavored examples
If do not have root access, you could use a crontab or a script with an infinite loop+sleep to run lsof & grep files in your homedir. See manpage of lsof. However, it will only display your applications that have a filedescriptor opened at the moment you launch lsof. Should an application open a file, edit it, then close it, you won't see this change in lsof.
a one-liner like this should do the job :
lsof -u $(id -u) 2>/dev/null |grep -P $HOME'/[^\s]*$'
Another way is to use the inotify kernel API to check when a file is being accessed. Alas, it's an async system, and you won't have details like "what app", "precisely when", "what user". You'll only have a callback about "this file was modified/accessed...". Some applications (Inotify, FAM, gamin) provides you simple access to the api