Off the top of my head, and I'll check references later on, elements of the SAS incluidng French SAS were inserted into France just before and after D-Day to assit the local Maquis in disrupting the German rear areas and start uprisings as the Allies advanced.
Edit: Google is a lot faster than searching through my bookshelves.
http://www.specialoperations.com/Foreign/United_Kingdom/SAS/Founding_Fathers.htm
Mayne's squadron sailed for the UK from Algiers in December 1943. Here it was decided to form an SAS Brigade and the SRS became the 1st SAS Regiment again, being expanded accordingly, with Mayne as a Lieutenant Colonel to command it. The other elements were to be 2SAS, who arrived a few months later, the French 3 and 4SAS, and the Belgian Independent Parachute Squadron(later 5SAS). The brigade would come under the command of I British Airborne Corps and changed to the maroon beret of the Airborne Forces. Mayne and some of his veterans didn't, wearing their beige berets whenever out of sight of the top brass.
After much conflict between the SAS commanders and the Airborne Forces staff( see below), it was decided to use the Brigade in its proper strategic role in the coming invasion of France. A special section was established at I Airborne Corps headquarters to coordinate its operations with those of Special Forces Headquarters(SFHQ), under which came the US Office of Strategic Services(OSS) and British Special Operations Executive(SOE) efforts in support of the invasion.
Of particular concern were the Jedburgh teams, three-man units whose mission was to liaise with and train the French Resistance. If possible each Jedburgh had one American, one Briton and one Frenchman (supplied by the Gaullist intelligence service, the BCRA ), but in practice this was not often achieved. Like the SAS and the OSS Operational Groups( OGs ) they usually operated in uniform. OGs were similar in many ways to the SAS; seven of these 34-strong teams were deployed in France from July to September 1944. They included Frenchmen as well as high proportion of Scandinavian-Americans, for they had originally been intended to operate in Norway.
A Squadron of 1SAS was the first full squadron into France on 21 June 1944, smaller parties having parachuted in before. Mayne was in soon afterward with a small headquarter patrol, linking up with different squadrons for operations all over Northern France. Squadrons established bases in woods and forests, having either parachuted in with their jeeps or infiltrated through German lines. They sometimes did so in cooperation with the local resistance, though the SAS found many resistance groups to be unreliable. From these bases attacks were launched on the German lines of communication, such as the mining of roads, destruction of railways and bridges, ambushes on convoys and sometimes raids on logistics centres and concentrations of troops. A typical camp had about fifty men in it, sometimes more. Mayne was behind enemy lines for most of the next four months and personally led many raids. He had a number of close calls, such as the time he and his patrol arrived to hide-up at a farmhouse only to find it occupied by Germans. A short firefight ensued but like Anders Lassen( see Cockleshell Heroes ), Mayne was a fearsome fighting soldier and his skills never let him down. Where the Germans were weak the SAS could establish liberated zones but often they found it harder to hide than in the vast spaces of North Africa. Also unlike in Libya and Tunisia, captured SAS men could expect little mercy- most were executed.
By the winter of 1944 most of 1SAS had either linked up with the advancing Allied forces or infiltrated back through the German lines by jeep or on foot. They had killed over a thousand Germans and destroyed a huge amount of equipment, as well as calling in many air strikes. There was little work for them over the winter as the front line stabilised and they were eventually sent back to the UK for a month.
and
http://www.answers.com/topic/special-air-service-1
In Operation Houndsworth, 144 SAS effectives parachuted with jeeps and supplies into Dijon, France. During and after D-Day they continued their raids against fuel depots, communications centres, and railways. They did suffer casualties — at one stage the Germans executed 24 SAS soldiers and a United States Army Air Forces pilot. At the end of the war, an SAS War Crimes Investigation Team, commanded by Major Eric Alistair 'Bill' Barkworth Somerset Light Infantry TA (Subsequently AAC) of 2 SAS traced all the SS and Gestapo personnel responsible for these killings and handed them over to the Allied authorities for trial as War Criminals.[N]
And some other bits and pieces
Op Gain - D Squadron, 1 SAS parachuted into southwest France to meet up with the Maquis and conduct operations to disrupt enemy communications. (1944)
Op Gaff - Seven members of 2 SAS parachuted into Ramouillet, France to kill or capture German Field Marshall Erwin Rommel at his headquarters at La Roche Guyon on the Siene. (25 July 1944)
http://www.specialoperations.com/Operations/opslist.html#anchor1561065
http://www.ampltd.co.uk/digital_guides/special_operations_executive_series_1_parts_1_to_5/Contents-of-Reels-Part-1.aspx
http://www.amazon.com/FIRE-FOREST-Brigade-Military-Paperbacks/dp/0304363367
