I tried to find info on this but had no success.
First of all, you’ll have no ads. Some people complain about the occasional ad-born virus that attacks the board so it might be helpful to think of your subscription as protection money. Second, you’ll experience an overwhelming sense of moral superiority over your fellow, less charitable Dopers. And finally, you’ll be relieved of burdensome money- just imagine, no worrying about what to do with the cash you spent subscribing!
Due to my many meaningful contributions to the board I was sponsored by a fellow Doper, so unfortunately I don’t receive the second and third benefits. But I have full access to the first.
Do you have to pay to see your post count?
I’m also wondering why no one has their pictures in their signatures.
Members have displayed post counts.
Because no one can have pictures in their signatures. You aren’t the first to wonder why; there has been many a great and violent battle waged over signature/avatar allowances. I suspect that within a few years we’ll have avatars, once the older and more curmudgeonly members have died.
By that time, the chronologically deprived whippersnappers will have aged enough to recognize the callow inanity of their youthish proclamations and will thus lead the campaign against avatars.
As for the OP: Us members get to have profile pictures.
Bless him, he thinks he’s still in WWII France. 
And don’t you forget it, sonny! Besides, avatars are for avatards.
To have it displayed, yes. As well as location.
Both post count and location may still be viewed in your profile by both you and others.
You also get the opportunity to pay even more to have a stupid joke under your name.
I like this board and I don’t mind giving $8 per year to support it.
This. Especially the second one. You also get to display a photo in your profile and, for only a little more, be eligible for a nifty title, as has been mentioned in another post.
BTW: I noticed a two-year membership is now an option but still only one year for the titles. Maybe those should match up? Two years for both?
You also get to start threads in the Marketplace Forum. See this thread for complete rules. Marketplace Rules - Marketplace - Straight Dope Message Board
You also get larger PM storage (100 vs 50). I found about that when my previous subscription expired, and people stopped being able to PM me.
Plus, it makes me not feel even the slightest guilt for running an adblocker on a site where I spend most of my Internet time. Oh, and it allows other people who want to pay even more for the Dope to sponsor you, since the board doesn’t accept donations.
Or $14.95 for us mere mortals.
I had a virus that came from (an ad on) this board that destroyed my work computer, and came close to costing me my job. Partially my own fault, I admit, although I don’t have permission to install the various kinds of preventative measures that are recommended here. I’m willing to pay a small fee to ensure that doesn’t happen again.
And you’ll keep payin’ on time if you knows what’s good fer ya!
Yeah, since I moved to guest status I feel my superiority complex slipping. I sometimes wish I hadn’t let my charter membership lapse, because that made me feel an ever more inflated sense of self worth. I guess I’ll just try to work it into conversations.
Much like this one.
Indeed, it does feel like protection money. But it’s a tiny amount per year, so I tolerate it. Especially since otherwise I really enjoy this board.
What about search? Is there still a 120-sec wait time between searches? About ~5% of the time my search times-out (problem on your side, SDMB? My internet connection is fine, I can assure you). In these cases I am forced to wait 120-sec to refine my search or try again.
This raises an interesting prospect. Why not allow members to search more frequently than guests?