Are there any other nice walks without going outside Sheffield other than Riverlin Valley and Endcliffe park?

Difficult one that John, You could try Millhouses Park or Hesley Wood near Chapletown.
You asked for Sheffield, one wonders why you don,t go into the Peak District which is doorstep paradise for walks.
Unfortunatly all the large wooded area,s are now gone in Sheffield although Wharncliffe Woods past Oughtabridge still has good walking areas large enough to spend a few good hours.

Treeton Dyke is a really nice place to go. It has a path around the lake and extensive woodland. You can find it just off the old A57 at Woodhouse Mill.

Eccellsall woods - park up on abbeydale rd nr Industrial Hamlet.

Round Walk - You can get on this at various places in Sheffield.

A good one is to go to Ringinglow rd park nr the Roundhouse and there is an old roman causeway over to Fox House, have a pint or an ice cream and come back (probably about 5 mile round trip)

Catch the bus to totley terminus, then cross the road and walk past the corner shop (which used to be a post office.) Walk straight on past the farm and the new developments and over the stile, then cross the fields up to the woods and over to Holmesfield it brings you out at the side of the "Angel" where you can have a pint before returning.

Alternatively, go to the "Sheply Spitfire" at the bottom of Mickley Lane and walk up the path at the side of the pub, it will take you up through the wood to the same place.

Also... Forge Dam... catch the 60 to the second stop after Nether Green school and it's a lovely walk... even if you can't find it!!
Also The Five Weirs walk.. that's quite a nice walk in Summer.
Chloé

If you like history and amazing city views try the Norfolk Trail - goes from the cathedral to Manor Lodge. There's a leaflet for it, but it's only in first draft. You should be able to pick it up from the Centre in the Park, Manor Lodge, and Sheff. Wildlife Trust HQ on Stafford RD. I'd post one out, but I'm not at work this week. 8) :D
Try CCCs or Waterstones - there are actually as lot of good walks in Sheffield. How about the 5 Weirs Walk...

I guess John means by 'nice' somewhere green - but by 'in Sheffield' within the urban area. Sheffield City Council website [look under Out & About, Maps] has a pdf showing all the parks & open spaces - there are apparently 78 parks in Sheffield.

I'd recommend taking a 51 all the way to Redmires [they don't all go all the way] which will give you a choice of walking on moorland, through woods & by water.

Also, check out the 'Sheffield links' on the left - there are 2 I spotted which should help - the Ramblers Association, and Walks in Sheffield which is right at the end of the list.

Since I posted this the links have been reorganised - but hopefully they are still in there somewhere.

These are great woods for roaming around in.

http://www.multimap.com/map/photo.cgi?client=public&X=436500&Y=384000&scale=10 000&width=500&height=310&gride=&gridn=

I would also strongly recommend the Norfolk Trail, I learnt so much about the history of Sheffield and had a top roast pork breadcake in the Norfolk Park cafe into the bargain. It's worth getting the little photocopied leaflet if you can find it, I think we picked ours up at the Graves gallery.
I mean, you know, a stroll round Florence it ain't, but we enjoyed it.

Another nice walk (if you avert your eyes from the litter) is Rivelin Roughs from round Den Bank way, overgrown old allotments, woods, dams and even a bit of moorland. I am grateful to our gay friends for enhancing this lovely spot with so many attractive KY jelly tubes and eco-friendly used condoms. Who could possibly fail to respect a lifestyle that makes such a contribution to the maintenance of our wild places? :?

Oh, and the old Walkley cemetery is fantastically atmospheric, especially the overgrown Jewish end. Access from Waller Road.

The Rivelyn and Loxley Valleys are lovely short walks - just get the tram to Malin Bridge.
I think you can still get a plastic wallet with maps and items of interest for £1 at the Tourist Shop on Union St.