It would be helpful for me simply to be able to tell at a glance, perhaps by link coloring, which records I've already viewed recently. Not have them disappear, just tell them apart. Ancestry.com does not use any "followed links" coloring on many of its screens, so both viewed and unviewed records look the same.
The suggestions of "related records" at the right side of a main record view often contains multiple records where the link title and descriptor are identical. (E.g., 4 records for Martha Fraley in the Kentucky Birth Index, or 6 records for James Lawson in the 1910 US Federal Census.) It quickly gets confusing as to which ones I've looked at, especially since they change their sort order depending upon which record is currently being viewed, and I often find myself redisplaying a record I've already processed. Since some of the databases index so few fields that you can't even tell them apart without viewing the image (e.g., many of the city directories), this can be time consuming. Worse yet, I fear I may accidentally overlook one of them because I lose track of where I was in the list and mistakenly think I've already looked at it.
(I do not keep a member tree on Ancestry, using it only for searching, so the record links I encounter are always in search results or related to another record.)
Link coloring is a minimal form of feedback, that is, better than nothing, but not ideal since it can only show two states. Better would be for the member history to maintain five states for previously viewed records:
A. Filter this record out, that is, do not display the link to the user.
B. Viewed, found relevant and processed - display link with a "done" indicator.
C. Viewed, found relevant but not yet fully processed - display link with a TBD indicator.
D. Viewed and found not relevant - display link with a negative indicator.
E. Viewed but no relevancy recorded - use viewed color or a viewed indicator.
States A-D would be attached explicitly by the user via some UI widget on the record display screen; state E would be the default for each viewed record for which the user set no other state.
(I would always use D in preference to A, since I would feel nervous about a link simply vanishing. Even if it is not relevant to me personally, I may want to return to it someday to gather a link to send to someone else saying "this record here is for the person you are interested in, who is not the same as the person of the same name you confused them with", which would be made difficult if I had set the link to be filtered out of my sight. But others may use Ancestry more narrowly, and want some records to just stay out of view.)
I realize, though, that such a feature could be a huge hit on the amount of data to be stored in the user history database, since some users view hundreds of records per day.