A few of my favorite utility modules are:
LA Circuits Machinist: Sample & Hold, Track & Hold, Slew, and several noise generators (Pink, Red, White, Blue, Violet), plus it has an LFO and clock generator.
Thorn Audio VCLFO: For starters it is an extremely powerful LFO with 16 different waveforms so even if you don't use its voltage control capability it's already a great modulation source. You can control it with CV to act as a more complex modulation source or use it as a bass VCO. It's syncable, it has a built-in octave offset function, generates noise & gates, and has S&H as well. It also has a built-in VCA on its output.
ADDAC216 Sum & Difference: This is a special mixer that allows you not just to add signals together like a standard mixer but also to subtract one from another. It has an attenuverter and offset on every input. It can operate in absolute or bipolar mode and can be AC or DC coupled so you can use it for audio or CV. A single module has two channels with two inputs each. This is quite a powerful module and it is not very expensive either.
Schlappi Engineering Boundary: This module can do a lot, at first glance it is a mini version of Maths, it has fewer channels but it is smaller and less expensive. But look closer and it has a few functions which Maths does not have. It has an AD envelope which can also be cycled to act as an LFO like Maths, but it has the ability to shape the rise and fall parts of the waveform independently, which Maths cannot do. It has a variety of other functions too, VCA, ring multiplier, and a lot more.
And of course the various "many in one" like the Disting and FX Aid series, ALM Busy Circuits MFX, and various fancier DSP modules come to mind. I'm not sure it's accurate to call all of those "utility" modules but many of them can perform a huge variety of functions in a relatively small footprint and that is very handy.