I found all of the below stamps in a two-block stretch of Broadway, the 1400 and 1500 blocks. As with Los Angeles, I bet there are thousands of these things in Denver.
Laid by Rick Beaver Const. 1980
Concrete Portland Cement Laid by L.E. Blanchard & Co.
Concrete Portland Cement Laid by L.E. Blanchard
P.J. Cawood Cement Contractor 1953
City Sidewalk Co. 67 (see below for further generations of City Sidewalk)
City Sidewalk Co. 73
City Sidewalk Co. 87
Denver Conc. Repair Co. 1964
Ideal Portland Cement Laid by Walt Flanagan
Laid by E.I. Gibbons Contractor 1989
Laid by H. &. H. Const. Co. Contractor 1964 (see below for 20 years later)
Laid by H. & H. Const. Co. Contractor 1984
Fred Harsli (?)
Laid by C.M. Hoppes 1954
Ideal Portland Cement Laid by R.E. Love
Ideal Portland Cement Laid by J.W. Love (related to R.E. Love, above?)
Naiman '73 -- a sidewalk scrape, but the ambition is similar
O. Napue 60
Laid by Ollus Construction Co. Contractor 1960 -- not sure this is Ollus, it is now under the building
Rogers Concrete 1970 -- this brass plate isn't exactly a sidewalk stamp, but here it is
Boyd Skelton
Ideal Portland Cement laid by G.A. Surber
R.J. Van Cleave & Sons 1957
Luke's Sidewalk Stamps, Other Cities: Bakersfield, California | Fresno, California | Los Angeles, California | Oakland, California | San Diego, California | San Francisco, California | Santa Barbara, California | Stockton, California | Seattle, Washington | Woodland, California