There are several ways to get more comfortable with the sound of your voice and get feedback. First, try Karaoke. Not sure where you live but I am sure there are venues which have Karaoke nights.
It was karaoke that made me realize I could sing better than average and started my journey into performing. It was the genuine feedback I got the first time I sang karaoke that made me aware that other folks thought I had a good voice and boosted my confidence.
So then I bought a karaoke machine and some CDG's and started singing at home which made me even better when I went to karaoke parties or karaoke nights at various venues.
This realization led me to learning guitar and later writing songs - but it all started with karaoke.
Another thing you can do if you are really brave, is post some video's of you singing on YouTube. Unless you disable comments - you will probably get feedback. Very honest feedback. Fortunately for me, I usually get good feedback on my voice. But once I tried to sing like an opera singer and I discovered how brutally honest the feedback on YouTube can be. I deleted that video! But if you get bad feedback on a particular performance, don't be discouraged. Try to learn from that experience and perhaps try a different song, or practice singing it differently or in a more comfortable key.
I don't know if they have Open Mic nights where you live, but they have those all over the U.S. - here is a link to a nationwide list (for those in the U.S.A.) [http://www.openmic.us/EventListing]
I regularly perform at open mics in my area and usually get feedback from the audience when I get off stage and sit back down. Folks will come up to me and say "good job man" or something like that. They don't come up to every performer - so I can tell that their compliments are genuine.
I have also learned that the more I sing in a "performance" situation, whether karaoke or open mic, the more comfortable I get singing and the better I get. I get more compliments now than I did when I first discovered that I could sing.
In your question you alluded to those who don't have great voices - but they don't let that stop them from singing. Don't worry so much about being a great singer. If you can sing and come close to staying in key - you are ahead of most. The main thing is to learn to enjoy singing without worrying so much about being on par with some of the greatest singers in the world.
Speaking of folks who don't have great voices - take Bob Dylan for example! A great song writer (true genius). He could have hired a professional studio vocalist to sing on his recordings, but he chose to sing them himself. Not to take anything away from Dylan as an artist, songwriter, and performer, but for me personally, his voice is a little harsh on most of the recordings I have heard (Lay, Lady Lay being a notable exception).
Most likely you already sound better than the great Bob Dylan. So sing early, sing late, sing often, and have fun singing whenever the opportunity presents itself.