I don't really do RSS, but here are some sites that I visit daily...

http://xkcd.com/
http://apod.nasa.gov/apod/ (NASA pic of the day)
http://www.metro.co.uk/games/nemi/
http://pixdaus.com/index.php?sort=best (nature photography, supposedly)
http://notalwaysright.com/
http://www.marriedtothesea.com/ (you already know)

...and weekly...

http://choppingblock.keenspot.com/
http://alienlovespredator.com/
http://textsfromlastnight.com/
http://www.fmylife.com/

...and then on livejournal...

http://riotclitshave.livejournal.com/ (worth checking back for some great images)
http://fantasygoat.livejournal.com/
http://tebe-interesno.livejournal.com/