This list is primarily the trails that go from Columbia River level to the top of the gorge.
There are more: I'll add them as I remember them

Angels Rest	Lower end: Road intersection near Bridal Veil Falls I-84 offramp  Upper end:  Various trails made by Trails Club ("Trillium Tr" etc) in Devils Rest area, off Palmer Mill Rd.  Also connections to Wahkeena/Multnomah Falls system of trails.	Well-maintained adjacent trails: some hard tofind
Wahkeena Falls Multnomah Falls	Lower end: Multnomah Falls Lodge (and Wahkeena Falls parking 1/4 mi to west) Upper end: Multnomah Basin, Larch Mtn, Franklin Ridge -- connections to trails east and west	Very well-maintained paved to ridge top
Oneonta Creek	Lower end: Horsetail Falls and trail parking just west of Oneonta Gorge Upper end:  Franklin Ridge and Yeon Mtn/Nesmith Point	Well-maintained
Rock of Ages Ridge See map below.	Lower end: About a  hundred yards north of Pony Tail Falls at sign "trail not maintained..." Upper end:  Mystery Trail -- Yeon Mtn Trail -- Horsetail Creek Trail	primitive trail, very steep in places--much poison oak near bottom
Mystery Trail	Lower end:  ?? -- near Ainsworth Park Upper end:  Rock of Ages Trail -- at sign "Mystery Trail" embedded in tree bark. Rock climbers trail for those climbing St Peters Dome and Rock of Ages.	Rope belay may be required.
Nesmith Point Tr.	Lower end:  Warrendale Upper end:  Nesmith Point:  roads to south closed to public use: Portland water supply.	well-maintained
Elowah Ridge	Lower end:  End of trail at top of upper Elowah Falls -- was a bush-whack job to a clearing from which the trail became quite clear (near some heavy equipment) Upper end:  Nesmith Point trail where it turns back away from the face of the Gorge.	difficult route: hard to fine at upper 2/3 point: routes fan out to get past an area of very steep moss-climbing
Munra Point	Lower end:  Highway bridge over Moffett Creek Upper end:  Munra Point, about 2000' elevation--end of ridge just west of Tanner Creek	steep, exposed climb
Tanner-Moffett	Lower end:  Tanner Ridge Road (below)--closed to public vehicular traffic Upper end:  Top of old Rd #436 at top of ridge near Mt Talapus--Could not locate in 1980 (ca.).	This was a primitive road used for power line maintenance.
Tanner Ridge	Lower end:  (Now) paved road near water tank just a little above Waclella (sp?) Falls Parking Upper end:  Tanner Butte and roads and trails south (roads are closed to public use);  Big Cedar	Maintained trails
Eagle Creek	Lower end: Eagle Creek trail head above fish hatchery Upper end: Wahtum Lake -- Tanner Ridge and Butte (see above) Side trail:  Eagle-Benson Trail to Benson Plateau	Well-maintained Extraordinary trail!
Ruckel Ridge See map below.	Lower end:  Upper end of Eagle Creek Campground Upper end:  Ruckle Creek Trail near top (Benson Plateau)	Primitive trail--has short knife-edge section
Ruckel Creek See map below.	Lower end:  Old Scenic Road just east of Eagle Creek campground  at stone bridge (Ruckel Ck) Upper end:  Benson Plateau	fair trail, but steep--possibly some maintenance
Rudolph Ridge See map below.	Lower end:  Poison oak patch on Dry Creek just below Falls (Town of Cascade Locks) Upper end:  Ruckel Creek Trail (About where Ruckel Ridge Trail meets the Creek Trail)--fried-egg marks on trees at top	very primitive route--can be very steep (exposed), especially if off route about half way up.
Benson Plateau Trail 2000 -- Pac Crest Tr.	Lower end:  Columbia Gorge Work Center--USFS Upper end:  Mexico Border -- but first, Wahtum Lake and points south Extensive trail complex on Benson Plateau	Well-maintained
Herman Creek Nick Eaton Ridge	A complex grid of many trails -- especially fine forests and views Lower end:  Columbia Gorge Work Center -- Herman Creek Campground Upper end:  Forest roads north of Mt Hood and south of Mt Defiance.  Rainy Lake	Some well-maintained. Some not.
North Lake	Lower end:  Wyeth Upper end:  North Lake -- Mt Defiance -- Rainy Lake	Well-maintained
Mt Defiance	Lower end: Starvation Creek trailhead.  (formerly Lindsey Ck, 1 mile to west)  1 route still goes that way (?). Upper end:  Mt Defiance--best route now via Cabin Creek ridge--Warren Lake and roads to south	Well-maintained
Viento Ridge	Lower end:  upper part of Viento State Park--lower route a maze of old logging roads Upper end:  Forest roads near Ditch and Phelps creeks--route almost impossible in 1985	maze of ephemeral old roads virtually impossible to follow
Wygant Trail	Lower end:  Vinzenz Lausmann Forest Park at Mitchell Point Upper end:  Forest Roads above Green Point Reservoir	poor trail in 1985 may have been improved?

USGS map of Horsetail Falls and Creek area.
Approximate route of Rock of Ages Ridge Trail in red.
The blue "?" and line is a guess as to the Mystery Trail location.  Rock of Ages itself
is just off the map to the north of the question mark.  The Horsetail Creek Trail is at
the lower-right corner of this map.  A short piece of the Rock of Ages Trail where it
leaves Horsetail Ck Tr is also shown.
 

USGS map of Ruckel and Rudolph Ridges area.
Approximate routes of Ruckle and Ruldolph ridge trails in reddish blue.
Ruckel Ridge trail (route) starts at upper end of campground near the power line.
Rudolph Ridge trail (route) leaves the Dry falls road through a shallow gully.  It is little more than a beaten path--it goes through quite a bit of poison oak.  When it turns left up to the ridge top, it is quite steep and somewhat exposed.  This is one of the more difficult routes in the Gorge.  It's often hard to locate--and it's steep and somewhat slick if wet.  It has painted circles on trees to locate the route for the last half mile or so at the top.
(Note the dotted route: that might be the correct way: I don't remember for sure.)