Tip I got from this forum: Wal-Mart sells a small dish rack (made for plates, I think) for like $2 or $3. It's in the aisle with plasticware, pitchers, glass, cooking dishes, etc. I think they call it a plate drying rack or something like that.
It's simple rubber coated metal wire, like any dish rack you've ever seen. Each one holds 8 "plates." If they are slim semi-auto pistols, you can line them up next to each other, but they fit close. I tend to leave an empty between handguns.
I have three of these in my safe and it's gotta be one of the best "simple, easy, cheap" solutions I've ever gotten from TFL.
In them is everything from my carry gun (fat subcompact Glock) to large frame revolvers to a T/C Contender with a 10-inch barrel and a 14" unmounted T/C barrel.
REALLY makes good use of the space in my safe. Maybe not quite as perfect as the racks marketed for use with handguns, but they check in at like half or a quarter of the price, or more. Some of the pretty wooden handgun racks I've seen (gorgeous!) go for $50-$75. These things cost less than three dollars.
Hell, for three bucks, you can buy one and try it and TOSS IT if it doesn't deliver.