There's a discussion going on at the moment as to whether old people should be made move out of their family homes to free them up for younger couples (which thankfully no one on that particular thread is endorsing). However it's a topic that has come up a number of times on MN with many posters bitterly begrudging the fact that old people are 'hogging' family sized homes, or that their parents' house is now worth ten times what they paid for it in 1972.
I have also seen posters complaining about elderly people using the supermarket at weekends or being in the post office at lunchtime, because they should leave these busy times to working people; questioning why their teenagers should offer seats to elderly people who travel for free; and in many ways belittling and being unpleasant about the older generation.
I know all generations get their stereotyping but some of the ageism is really unpleasant. It's a minority of posters but their begrudging, bitter and hostile attitude towards the elderly can be really depressing to read.