Great stories, especially those last two by glock and djtitis. Two of my earliest are the most memorable.
1) I had just moved into a new city in the mid-1990s, and started dating via phone chat lines to meet women right away. Shelly invited me to her small home since she had two young kids and couldn't leave the house. She wasn't very hot-looking (not that I'm Brad Pitt myself), and we had little in common but the need for sex, but accepted this encounter for what it was. After chatting for a while in her bedroom, she started stroking me, then took a phone call; while she talked I repositioned myself over her chest while she kept jacking me. When the phone call ended, she pulled me into her mouth and swallowed my cum. We slept, then in the morning before she went to work I said I wanted to cum on her face, so I assumed the same position and jacked off while she stared at me. After a few minutes I burst out onto her chin, a big glob sticking right under her lips. Her neutral expression went unchanged, and she kept it on for several minutes as she started to get dressed to let me see and appreciate it. It felt a little weird, but also satisfying to mark her face in that way. I only saw her 1-2 times after that, but always appreciated her kindness to me.
2) Three years later, just months before leaving that same city for another, I used an online matchmaking service to find a girl, Derren, who shared my love of Walt Whitman. We didn't actually meet until after her 18th birthday, but then she met me once with a friend and then fooled around in a car briefly. She was a little chubby but always had a gorgeous smile on her face, and 20 years later remains youthful and good-looking (unfortunately we could only rarely meet after I moved and we've each found other partners, though we are still in touch). On our third visit she came to my house on my 30th birthday, which unfortunately was I otherwise spending alone. She called while I was lounging around undressed, so I hastily got in the shower, and had barely finished when the doorbell rang so I wrapped a towel around my waist to meet her at the door. We sat on the couch for a few minutes to talk but she was soon rubbing the exposed side of my leg, making my dick hard as a rock and tenting through the towel. I turned to straddle over her, the towel quickly fell off with her help, and after a minute of stroking she said she wanted to see what I tasted like, and started sucking me. This began about an hour of blowjobbing in various positions--me over her, her over me, on the couch, on the floor, me on the couch with her on the floor, etc., and finally me over her again as she lay back on my bed. She made it clear from the beginning that I was her first, and she wanted to just suck me, and wasn't ready to have cum in her mouth. I respected this and held back, never pushing for orgasm but just enjoying her exploration of my dick and her ability to manipulate it with her mouth and hands. Finally as I was feeling her gentle sucking under me I decided I wanted to cum. I said "Derren...?" She pulled me out to ask what I wanted, and I then asked if I could cum on her face. She thought for a few seconds and then said "yes." I took matters in my own hand for the first time and began stroking my shaft only an inch from her face as she stared at my cockhead with curiousity and passive anticipation. I intended to pull back further and paint her more generally when I was ready, but after such a long build-up the intensity was so great I couldn't fully control it, and the first extremely fast and focused squirt of cum hit her directly on her closed lips, immediately spreading along the crack from right to left and forming a line of organic white lipstick over her mouth. Several more squirts pulsed out around her mouth as I cried with pleasure and stared at the mess I was making. She kept her mouth closed for a minute as I enjoyed the sight, which all too soon--again, respecting her desire to keep the cum out of her mouth--I got a towel to wipe her face off with. So it didn't last as long as the first facial above, but the target was far more sexy and the tension between avoiding an inside-mouth cum shot and wanting to nevertheless get my semen in intimate contact with her was incredibly powerful, and the lipstick-style cumshot was one of the best I've ever made.