I would much rather redo a bit of the hacking guide or actually do/finish the companion piece on hardware hacking with an eye to doing more on case/mechanical/materials engineering and audio/video/repair/adapting side of things rather than the security systems stuff.
Also after
http://wiki.gbatemp.net/wiki/GBAtemp.net#History there is not much to really expand upon unless you want to go into the people side of things (though it misses several prominent non staff members then
http://wiki.gbatemp.net/wiki/Former_Staff_members ) and if you pick a random sample of non TA/EOF posts from them you can usually get a good idea of them. Actually maybe some of the features which I tried to collect together in
http://gbatemp.net/threads/links-to-various-gbatemp-features-over-the-years.352851/ might also warrant being looked at. You could go into the more day to day stuff but that usually amounts to "is it e3 or something of similar importance? Look into that if so. Otherwise there is no such thing as too much content*.".
I guess you could try to tease out some of the history -- some looked oddly at us when we started going after reviews proper back in March 2014 but between those features already mentioned and the release lists in general then it was basically a formality.
I also have a choice link but I am not sure where to crowbar it into all that
http://gbatemp.net/threads/does-gbatemp-have-a-rival-forum.355250/page-2#post-4785064
*a common phrase pertaining to website/web community development would be "'build it and they will come' does not apply to the internet, 'build and make sure there is always new content' does apply though".