As the
Titanic's passengers came from a number of nations, you'd be hard pressed to find a site online that had all this information compiled. There's quite a bit of it in the ET bios, but you may need to trawl through the records yourself.
You can find, for example, the 1891 British census on-line:
freecen.rootsweb.com
Eventually Rootsweb aims to transcribe all the census entries for England.
The Public Records Office (PRO) has also recently made the 1901 census available on-line. You can do a basic search for free, but will need to pay to see the full details for the entries:
census.pro.gov.uk
Census UK has some resources:
Census records for 1851, 1881 1891 1901 and the Vital Record Index
web.archive.org
Senan Molony published a good many census returns for the Irish crew and passengers in his book
The Irish Aboard Titanic. Here's some on-line information:
Census returns for 1851, 1881 and the Vital Record Index
web.archive.org
Here's a US site, although I've never used it and can't vouch for it:
The USGenWeb Census Project®
I'm not sure what you mean by wanting sites that have family members 'up to present descendants'. Census returns are usually sealed for a lenghty period after they are compiled. In the UK, for example, this is for 100 years, which is why the 1901 returns have only just been published.