Renato,
as Dana says, the question "how many ways can nature make a massive (10000 solar masses or more) and centrally-concentrated 'globular-like' star cluster?" is hard to answer.
In my opinion , nature can certainly make "brand new" globular clusters in galaxy merger events, as there is now abundant observational evidence - in several well-studied elliptical galaxies - that there do exist genuine globular star clusters that are
substantially younger than the canonical "9-13 billion years old"
old age of the globulars found in the MW and M31 and M81 and M104.
(NGC 1316 has plenty of these intermediate-aged globulars, and NGC 5128 has a few)
It is also confirmed that a merger between two large galaxies can result in the
recent formation of young star clusters that weigh in at 1 million solar masses (or more) per star cluster. Well studied examples are NGC 4038/4039 and NGC 7252.
[[ Many of the star clusters formed in these collossal galaxy collisions will actually dissolve, eventually (Dana knows a lot more about star cluster dissolution than I do) ]]
The Nuclear Star Clusters (NSCs) which are often found at the very centres of types Sc to Sm spiral galaxies (e.g in NGC 7793, NGC 300, NGC 4449, NGC 1705), according to multiple papers by Torsten Boker and colleagues (a group who have been working this problem for a long time) have been
thought to be about the same size as standard globular clusters, though the most luminous NSCs have a substantially greater
luminosity than even the brightest "standard old" globular cluster. (Some particularly luminous NSC have an impressive absolute V magnitude of minus 15). Also, an NSC can very obviously contain multiple populations of stars which were formed at various times, as compared to a globular, which usually (though not always!) contains a single population of stars that formed at the same time.
BUT>>>>>
there also exist star-cluster-like objects that can get
larger than even the largest known globular star cluster: :
(1) Ultra Compact Dwarf (UCD) galaxies
(2) Nuclei of elliptical galaxies
( technically speaking, the radius of some of these objects is well outside of the usual range of effective radii that is occupied by the population of globular star clusters)
A particularly prominent example of an UCD galaxy was imaged by IIS member Rolf:
http://www.iceinspace.com.au/forum/s...t=92183&page=3