if you r looking specifically for tax lien properties there is no one website that lists properties that have liens against them. this is actually how i invest. you need to contact the tax collector for the town you want to research liens in. you need to get the most recent tax sale list or upcoming list if its i the future. if the sale has passed you need to have them give you the results of the sale. which properties did have liens placed against them. if its a future sale, i would plan on attending it. you can buy some liens yourself if you would like. however, at the very least go there to record which liens were placed. once i have my list, i check with tax collector to see if there are older liens on a property. e. g. if you have the tax sale list for 2012 i'll ask if there are any liens prior to 2012. you do this so that properties that are coming close to the foreclosure date, you can heavily market to. these owners will be more likely motivated b/c they are close to losing their property to foreclosure. back to websites, most tax collector offices will either mail/email you sale list. also a lot of times, they are posted on regional paper (ac press, ap press, etc). occassionally, you will get lucky and they'll post the tax sale list right on the townships website. hope this helps. sorry for length.
as far as foreclosed properties, you can just google foreclosure lists, and im sure you will find some. most of the ones i have seen require a monthly fee. you could also use a realtor, zillow, trulia, or other listing sites usually post foreclosures.
