A few quick and easy ways I sometimes use:
last.fm recommended artists, try and filter through it to get to artists you haven't heard of.
RateYourMusic.com - Such an underrated tool for exploring music 9apart from the dreadful forum). It is so much more than a site to list your music collection. Once you have listed what you have you can then:
See who else has similar tastes to you and then browse their collection and see if anything grabs your interest.
Browse thousanRAB of lists from 'favourite albums' to very specific ones. Aim to find the lists that have a note for each album, explaining why it is good or what it means to that person i.e. ones like this
The albums every record collection should have:1965-2006 - Rate Your Music. not a bad place to start if your collection isn't big, but these little notes are more valuable than just a list of albums with no comments.
Click on the albums, read the reviews etc. At the bottom will be a list of other lists that the album appears on, try and view ones that look as though they will contain similar albums.
View the RYM top albums list, by all time or specific decade or year, or create a custom one by genre and other specifics.
The home page contains several well written reviews on random albums, a lot are even obscure and may interest you.
These are just a few of the ways this site can help you and I'm sure there are plenty of others I am forgetting off the top of my head.
Hope this helps in some way.